Composition of antibodies with high ADCC

The present invention relates to a method for obtaining and selecting monoclonal antibodies by an ADCC type test, said antibodies being capable of activating Fcγ type III receptors. The invention also relates to monoclonal antibodies having a particular glycan structure, the cells producing said antibodies, methods for preparing the producer cells, as well as pharmaceutical compositions or diagnostic tests comprising said antibodies. The anti-D antibodies according to the invention can be used for the prevention of Rh-isofrequency of Rh-negative individuals, in particular of the haemolytic disease of the newborn (MHNN) or in applications such as Idiopathic Thrombocytopenic Purpura (ITP). .

Passive immunotherapy with polyclonal antibodies has been carried out since the 1970s. However, the production of polyclonal immunoglobulins poses several problems:<ul id="ul0001" list-style="none" compact="compact"><li>Immunization of volunteers was interrupted in France in 1997 because of the ethical problems of such acts. In France, as in Europe, the number of immunized donors is too small to ensure a sufficient supply of certain antibodies so that it is necessary to import hyperimmune plasma from the United States for example.</li><li>Thus, this shortage of immunoglobulin does not make it possible to envisage an antenatal administration for the prevention of the MHNN.</li></ul>

Various studies have resulted in the production of human monoclonal antibodies to replace polyclonal antibodies obtained from the fractionation of plasma from volunteer donors.

Monoclonal antibodies have several advantages: they can be obtained in large quantities at reasonable prices, each batch of antibody is homogeneous and the quality of the different batches is reproducible because they are produced by the same cell line which is cryopreserved in nitrogen liquid. Product safety can be ensured regarding the absence of viral contamination.

Several publications describe the production of cell lines producing human IgG anti-Rh D monoclonal antibodies from immunized donor B cells. Boylston et al. 1980 ; Koskimies 1980; Crawford et al. 1983 ; Doyle et al. 1985 ; Goossens et al. 1987 ; Kumpel et al. 1989 (a) and Mc Cann-Carter et al. 1993 describe obtaining EBV-transformed B cell lines. Melamed et al. 1985 ; Thompson et al. 1986 and Mc Cann-Carter et al. 1993 relate to hetero-hybrids resulting from fusion B-lymphocytes (transformed by EBV) x murine myeloma. Goossens et al. 1987 relates to hetero-hybrids resulting from fusion of B-lymphocytes (transformed by EBV) x human myeloma. Bron et al. 1984 and Foung et al. 1987 describe heterobybrids resulting from fusion of B-lymphocytes (transformed with EBV) x human-mouse heteromyeloma and finally, Edelman et al. 1997 relates to insect cells transfected with the gene encoding an anti-Rh (D) using the baculovirus system.

Among the patents and patent applications concerning such monoclonal antibodies and their secretory lines, mention may be made of:<ul id="ul0002" list-style="none" compact="compact"><li>EP 576093 (AET S (FR), Biotest Pharma GmbH (Germany), Composition for prophylaxis of the haemolytic disease of the newborn comprising two human monoclonal antibodies of subclass IgG1 and IgG3, which are active against the Rhesus D antigen) , UK 2094462, WO 85/02413 (Board of Trustees of the Leland Stanford Jr. University Human Monoclonal Antibody against Rh (D) Antigen and its Uses), GB 86-10106 (Central Blood Laboratories Authority, Production of heterohybridomas for human monoclonal antibodies to Rhesus D antigen), EP 0 251 440 (Central Blood Laboratories Authority, Human Anti-Rhesus D Producing Heterohybridomas), WO 89/02442, WO 89/02600 and WO 89/024443 (Central Blood Laboratories Authority, Human Anti-Rh (D) Monoclonal Antibodies), WO 8607740 (Pasteur Institute, Protein Performance SA, Paris, EN, Obtaining a recombinant monoclonal antibody from a human anti-rhesus D monoclonal antibody, its production in insect cells and its uses), JP 88-50710 (International Reagents Corp., Japan, Reagents for Determination of Blood Group Substance Rh (D) Factor), JP 83-248865 (Mitsubishi Chemical Industries Co., Ltd. Japan, Preparation of Monoclonal Antibody to Rh (D) Positive Antigen, CA 82-406033 (Queens University at Kingston, Human Monoclonal Antibodies) and GB 8226513 (University College London, Human Monoclonal Antibody Against Rhesus D Antigen).</li></ul>

While the use of monoclonal antibodies has many advantages over the use of polyclonal antibody pools, it can be difficult to obtain an effective monoclonal antibody. Indeed, it has been found in the context of the invention that the Fcγ fragment of the immunoglobulin obtained must have very particular properties in order to be able to interact and activate the effector cell receptors (macrophage, TH and NK lymphocyte).

The biological activity of certain immunoglobulins G is dependent on the structure of the oligosaccharides present on the molecule, and in particular on its part Fc. The IgG molecules of all human and murine subclasses have a N-oligosaccharide attached to the CH domain₂ each heavy chain (at residue Asn 297 for human IgG). The influence of this glycannic residue on the ability of the antibody to interact with effector molecules (Fc receptors and complement) has been demonstrated. The inhibition of glycosylation of a human IgG1, by culture in the presence of Tunicamycin, causes for example a 50-fold decrease in the affinity of this antibody for the FcγRI receptor present on monocytes and macrophages (Leatherbarrow et al, 1985). . FcγRIII receptor binding is also affected by the carbohydrate loss on IgG, since it has been described that unglycosylated IgG3 is unable to induce ADCC-type lysis via the FcγRIII receptor of NK cells. (Lund et al, 1990).

But, beyond the necessary presence of these glycan residues, it is more precisely the heterogeneity of their structure that can lead to differences in the ability to engage effector functions. Variable galactosylation profiles according to individuals (serum human IgG1) were observed. These differences probably reflect disparities in the activity of galactosyltransferases and other enzymes between the cell clones of these individuals (Jefferis et al, 1990). While this normal heterogeneity of post-translational processes generates different glycoforms (even in the case of monoclonal antibodies), it can lead to atypical structures associated with certain pathological conditions such as rheumatoid arthritis, Crohn's disease, for which a significant proportion of agalactosyl residues have been identified (Parekh et al, 1985). The glycosylation profile of the purified molecule is the consequence of multiple effects, some parameters of which have already been studied. The IgG protein backbone and in particular the amino acids in contact with the N-acetylglucosamine (GlcNAc) and galactose residues of the α 1-6 mannose arm (aa 246 and 258 of IgG) can explain the existence of preferential structures (galactosylation). as shown by the study on murine and chimeric IgG of different isotypes (Lund et al, 1993).

The observed differences also highlight specificities related to the species and cell type used for the production of the molecule. Thus, the classical structure of the N-glycans of human IgG reveals a significant proportion of biantennary types with a GIcNAc residue in the bisecting position, a structure absent in the antibodies produced by murine cells. Similarly, the sialic acid residues synthesized by the CHO (Chinese Hamster Ovary) line are exclusively of the α 2-3 type whereas they are of the α 2-3 type and α 2-6 with the murine and human cells ( Yu Ip et al, 1994). The production of immunoglobulins in expression systems other than those derived from mammals can introduce much larger modifications such as the presence of xylose residues made by insect cells or by plants (Ma et al, 1995).

Other factors such as cell culture conditions (including the composition of the culture medium, cell density, pH, oxygenation) appear to affect the glycosyltransferase activity of the cell and consequently the glycan structure of the cell. molecule (Monica et al, 1993, Kumpel et al, 1994b).

However, it has been found in the context of the present invention that a biantennate-type structure, with short chains, low sialylation, terminal mannoses and / or non-intermediate terminal GlcNAc is the common denominator of the glycan structures conferring high activity. ADCC to monoclonal antibodies. A method for the preparation of such antibodies capable of activating the effector cells via FcγRIII, in particular anti-Rh (D) antibodies, has also been developed.

The blood group antigens are classified into several systems depending on the nature of the membrane molecules expressed on the surface of red blood cells. The Rh system (Rh) comprises 5 molecules or antigens: D, C, c, E and e (ISSITT, 1988). D antigen is the most important of these molecules because it is the most immunogenic, that is to say, it can induce the production of anti-D antibodies if Rh D positive red blood cells are transfused to Rh negative subjects.

D antigen is normally expressed in 85% of Caucasoid subjects, these people are called Rh positive; 25% of these subjects are Rh negative that is to say that their red blood cells do not present D antigen. The expression of the D antigens has certain variants which may be linked either to a low antigenic density, we will then speak of weak D antigens, or to a different or partial antigenicity, we will then speak of partial D antigens. The weak D character is characterized by the fact that it is a normal antigen but whose number of sites per red blood cell is decreased to a greater or lesser extent; this character is transmissible according to the Mendelian laws. Partial D phenotypes were found in Rh D positive subjects who possessed serum anti-D antibodies; these partial D antigens can therefore be characterized as possessing only part of the mosaic. Studies carried out with polyclonal and monoclonal antibodies have made it possible to define 7 categories of partial D antigens with the description of at least 8 epitopes constituting the D antigen (LOMAS et al. 1989 ; TIPETT 1988).

The importance of anti-Rh D antibodies arose with the discovery of mechanisms leading to haemolytic disease of the newborn (MHNN). This corresponds to the different pathological conditions observed in certain fetuses or in certain newborns when there is a fetomecoronergic blood group incompatibility which is responsible for the formation of maternal anti-Rh D antibodies capable of crossing the barrier. placenta. Indeed, the passage of Rh positive fetal red blood cells in an Rh negative mother can lead to the formation of anti-D antibodies.

After immunization of the Rh negative mother, the anti-D IgG class antibodies are able to cross the placental barrier and bind to the Rh positive fetal red cells. This binding leads to the activation of immunocompetent cells via their surface Fc receptors, thus inducing hemolysis of sensitized fetal red cells. Depending on the intensity of the reaction, several degrees of severity of the NHHN can be observed.

A diagnosis of the NHHN can be made before and after birth. Prenatal diagnosis is based on changes in maternal anti-D antibody levels using several immunohematological techniques. Postpartum diagnosis can be done from a cord blood sample by analyzing the following parameters: determination of fetal and father blood groups; search for anti-D antibodies; dosages of hemoglobin and bilirubin.

Prophylaxis of HRHN is currently routinely performed in all Rh-negative women with an Rh-positive child with human anti-D immunoglobulin injections. The first real trials of immunoprophylaxis began in 1964. For prevention to be effective, it is necessary that the immunoglobulins are injected before the immunization that is to say in the 72 hours which follow the delivery and that the doses of antibodies are sufficient (10 μg of antibodies anti -D for 0.5 ml of Rh + red blood cells).

Several anti-D monoclonal antibodies have been therapeutically evaluated: BROSSARD / FNTS 1990 (unpublished); THOMSON / IBGRL 1990; KUMPEL / IBGRL 1994; BELKINA / Institute of Hematology Moscow 1996; BIOTEST / LFB 1997 (unpublished). The clinical efficacy of antibodies to induce Rh (D) positive RBC clearance was assessed in Rh (D) negative volunteers. A single IgG1 antibody showed efficacy equivalent to anti-D polyclonal immunoglobulins but only in a few patients (KUMPEL et al, 1995).

The invention proposes to provide monoclonal antibodies answering the abovementioned problems, that is to say antibodies selected by a specific ADCC type test and / or antibodies having a glycan structure necessary for obtaining a good efficiency.

Description

Thus, the present invention relates to a process for preparing a monoclonal antibody capable of activating the effector cells expressing FcγRIII, characterized in that it comprises the following steps:<ul id="ul0003" list-style="none" compact="compact"><li>a) purification of monoclonal antibodies obtained from different clones originating from cell lines selected from hybridomas, in particular hetero-hybridomas, and animal or human cell lines transfected with a vector comprising the gene coding for said antibody;</li><li>b) adding each antibody obtained in step a) to a separate reaction mixture comprising:<ul id="ul0004" list-style="dash" compact="compact"><li>the target cells of said antibodies,</li><li>effector cells comprising cells expressing FcγRIII,</li><li>polyvalent IgGs,</li></ul></li><li>c) determination of the percentage of lysis of the target cells and selection of the monoclonal antibodies which activate the effector cells causing a significant lysis of the target cells (FcγRIII type ADCC activity).</li></ul>

The clones can come from hetero-hybrid cell lines obtained by fusion of human B lymphocytes (from immunized subjects) with murine myeloma cells, human or heterohybrid, in particular myeloma K6H6-B5 (ATCC No. CRL 1823); or else animal or human cell lines transfected with a vector containing the gene coding for an IgG-type human immunoglobulin, said lines which can be selected in particular from the CHO-K lines, CHO-Lec10, CHO Lec-1, CHO Pro-5, CHO dhfr-, Wil-2, Jurkat, Vero Molt-4, COS-7, HEK-293, YB2 / 0, BHK, K6H6, NSO, SP2 / 0-Ag 14 and P3X63Ag8.653.

The polyvalent IgGs are used to inhibit the mechanism of lysis of effector cells via FcγRIII. In this process, antibodies having a FcγRIII type ADCC level of greater than 60%, 70%, 80% or preferably greater than 90% are selected. The target cells may be red cells treated with papain. In this case, one deposits per well:<ul id="ul0005" list-style="dash" compact="compact"><li>100 μl of monoclonal antibodies purified to about 200 ng / ml,</li><li>25 μl of papainous red blood cells, approximately 1x10⁶ cell</li><li>25 μl of effector cells, approximately 2x10⁶ cell</li><li>and 50 μl of polyvalent IgG, in particular TEGELINE ™ (LFB, France), at a concentration of between 1 and 20 mg / ml.</li></ul>

It is thus possible to compare the amount of lysis of the target cells with two positive controls consisting of a chemical compound such as NH₄Cl and an active reference antibody <i>in vivo</i> and a negative control consisting of an inactive antibody <i>in vivo.</i>

Commercial polyclonal antibodies can also be used as positive controls and a monoclonal antibody that is incapable of inducing clearance. <i>in vivo</i> as a negative witness.

Advantageously, this method makes it possible to prepare monoclonal antibodies against Rh (D), as indicated previously. Rhesus D cells are then used as target cells.

The invention is therefore based on the development of a biological activity test <i>in vitro</i> in which the measured activities correlate with the biological activity <i>in vivo</i> monoclonal or polyclonal antibodies already clinically evaluated for their potential to induce clearance of Rh (D) positive red blood cells in Rh (D) negative volunteers. This test makes it possible to evaluate the antibody-dependent lytic activity = ADCC (Antibody Dependent Cellular Cytotoxicity) induced essentially by Fcγ receptors of type III (CD16), the Fcγ receptors of type I (CD64) being saturated by the addition of human IgG immunoglobulins (in the form of therapeutic polyvalent IgGs). The FcγRIII specificity of this ADCC test was confirmed by inhibition in the presence of anti-FcγRIII monoclonal antibody (see FIG. 6). Mononuclear cells from healthy subjects are used as effector cells in an effector / target (E / C) ratio close to physiological conditions <i>in vivo.</i> Under these conditions the lytic activities of the polyclonal immunoglobulins and the ineffective anti-D monoclonal antibodies <i>in vivo</i> (Goossens DF5 antibody et al., 1987 and antibodies AD1 + AD3, FR 9207893 LFB / Biotest and FOG-1, GB 2189506) are respectively strong and weak.

The selection of the antibodies described in the present invention was therefore carried out by evaluating their biological activity in this ADCC type test (see Example 1).

In another aspect, the invention relates to the antibodies obtainable from the method described above, said antibodies having FcγRIII type ADCC levels greater than 60%, 70%, 80% or preferably greater than 90%. % relative to the reference polyclonal. The monoclonal antibodies of the invention, directed against a given antigen, activate the effector cells expressing FcγRIII causing lysis greater than 60%, 70%, 80%, preferably greater than 90% of the lysis caused by directed polyclonal antibodies. against said antigen. Advantageously, said monoclonal antibodies are directed against rhesus D. They can preferably be produced by clones derived from the Vero (ATCC No. CCL 81), YB2 / 0 (ATCC No. CRL 1662) or CHO Lec-1 (ATCC No. CRL 1735) lines and may belong to the IgG1 class. or IgG3.

The invention also relates to antibodies having a particular glycan structure conferring FcγRIII-dependent effector activity. Such antibodies can be obtained from a process explained above and have on their glycosylation site (Asn 297) of Fcγ glycan structures of the biantennary type, with short chains and low sialylation. Preferably, their glycan structure has end terminal mannoses and / or GlcNAc non-intercalary terminals.

Such antibodies are more particularly selected from the forms:<img file="EP1518864A2_D0001.tif" />

Thus, the invention relates to a monoclonal antibody characterized in that it has at its glycosylation site (Asn 297) of Fcγ glycan structures of biantennary type, with short chains, low sialylation, mannoses and GlcNAc of the d non-spacer terminals. Said antibodies, directed against a given antigen, activate the effector cells expressing FcγRIII causing lysis greater than 60%, 70%, 80%, preferably greater than 90% of the lysis caused by polyclonal antibodies directed against said antigen.

More particularly, the invention relates to antibodies and compositions comprising said antibodies as defined above, wherein the sialic acid content is less than 25%, 20%, 15%, or 10%, preferably 5% , 4% 3% or 2%.

Similarly, the invention relates to antibodies and compositions comprising said antibodies as defined above, wherein the fucose content is less than 65%, 60%, 50%, 40%, or 30%. Preferably, the fucose content is between 20% and 45% or between 25% and 40%.

A particularly effective composition according to the invention comprises, for example, a content greater than 60%, preferably greater than 80% for the forms G0 + G1 + G0F + G1F, it being understood that the forms G0F + G1F are less than 50%, preferably less than 30%. <tables id="tabl0001" num="0001"><table frame="all"><title>Table 1:</title><tgroup cols="9" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="17.50mm" /><colspec colnum="2" colname="col2" colwidth="17.50mm" /><colspec colnum="3" colname="col3" colwidth="17.50mm" /><colspec colnum="4" colname="col4" colwidth="17.50mm" /><colspec colnum="5" colname="col5" colwidth="17.50mm" /><colspec colnum="6" colname="col6" colwidth="17.50mm" /><colspec colnum="7" colname="col7" colwidth="17.50mm" /><colspec colnum="8" colname="col8" colwidth="17.50mm" /><colspec colnum="9" colname="col9" colwidth="17.50mm" /><thead valign="top"><row><entry namest="col1" nameend="col9" align="center"><b>quantification (%) of the oligosaccharide structures of the different Anti-RhD antibodies</b></entry></row><row><entry namest="col1" nameend="col6" align="center"><i>Active Antibodies in ADCC FcRγIII</i></entry><entry namest="col7" nameend="col9" align="center"><i>Inactive antibodies in ADCC FcRγ</i>III</entry></row><row><entry namest="col1" nameend="col1" /><entry namest="col2" nameend="col2" align="center">R 297</entry><entry namest="col3" nameend="col4" align="center">R 270</entry><entry namest="col5" nameend="col6" align="center">F60</entry><entry namest="col7" nameend="col8" align="center">D 31</entry><entry namest="col9" nameend="col9" align="center">F5</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Structure</entry><entry namest="col2" nameend="col2" align="center">HPCE-LIF</entry><entry namest="col3" nameend="col3" align="center">HPCE-LIF</entry><entry namest="col4" nameend="col4" align="center">HPLCs</entry><entry namest="col5" nameend="col5" align="center">HPCE-LIF</entry><entry namest="col6" nameend="col6" align="center">HPLCs</entry><entry namest="col7" nameend="col7" align="center">HPCE-LIF</entry><entry namest="col8" nameend="col8" align="center">HPCE-LIF</entry><entry namest="col9" nameend="col9" align="center">HPLCs</entry></row><row><entry namest="col1" nameend="col1" align="left"><i>fucosylated</i></entry><entry namest="col2" nameend="col2" align="center">34.3</entry><entry namest="col3" nameend="col3" align="center">45.9</entry><entry namest="col4" nameend="col4" align="center">37.2</entry><entry namest="col5" nameend="col5" align="center">47.7</entry><entry namest="col6" nameend="col6" align="center">46.6</entry><entry namest="col7" nameend="col7" align="center"><b>82.0</b></entry><entry namest="col8" nameend="col8" align="center"><b>88</b></entry><entry namest="col9" nameend="col9" align="center"><b>100</b></entry></row><row><entry namest="col1" nameend="col1" align="left"><i>sialylated</i></entry><entry namest="col2" nameend="col2" align="center">1.0</entry><entry namest="col3" nameend="col3" align="center">2.2</entry><entry namest="col4" nameend="col4" align="center">4.1</entry><entry namest="col5" nameend="col5" align="center">9.9</entry><entry namest="col6" nameend="col6" align="center">19.6</entry><entry namest="col7" nameend="col7" align="center"><b>47.9</b></entry><entry namest="col8" nameend="col8" align="center"><b>52.0</b></entry><entry namest="col9" nameend="col9" align="center"><b>47</b></entry></row><row><entry namest="col1" nameend="col1" align="left">G2S2FB</entry><entry namest="col2" nameend="col2" /><entry namest="col3" nameend="col3" /><entry namest="col4" nameend="col4" /><entry namest="col5" nameend="col5" /><entry namest="col6" nameend="col6" /><entry namest="col7" nameend="col7" /><entry namest="col8" nameend="col8" /><entry namest="col9" nameend="col9" align="center">2.8</entry></row><row><entry namest="col1" nameend="col1" align="left">G2S2F</entry><entry namest="col2" nameend="col2" align="center">0.0</entry><entry namest="col3" nameend="col3" align="center">0.0</entry><entry namest="col4" nameend="col4" align="center">nd</entry><entry namest="col5" nameend="col5" align="center">4.2</entry><entry namest="col6" nameend="col6" align="center">0.0</entry><entry namest="col7" nameend="col7" align="center">11.3</entry><entry namest="col8" nameend="col8" align="center">11.9</entry><entry namest="col9" nameend="col9" align="center">4.1</entry></row><row><entry namest="col1" nameend="col1" align="left">G2S1FB</entry><entry namest="col2" nameend="col2" /><entry namest="col3" nameend="col3" /><entry namest="col4" nameend="col4" /><entry namest="col5" nameend="col5" /><entry namest="col6" nameend="col6" /><entry namest="col7" nameend="col7" /><entry namest="col8" nameend="col8" /><entry namest="col9" nameend="col9" align="center">6.1</entry></row><row><entry namest="col1" nameend="col1" align="left">G2S1F</entry><entry namest="col2" nameend="col2" align="center">1.0</entry><entry namest="col3" nameend="col3" align="center">1.0</entry><entry namest="col4" nameend="col4" align="center">nd</entry><entry namest="col5" nameend="col5" align="center">2.7</entry><entry namest="col6" nameend="col6" align="center">2.5</entry><entry namest="col7" nameend="col7" align="center"><b>21.4</b></entry><entry namest="col8" nameend="col8" align="center"><b>30.5</b></entry><entry namest="col9" nameend="col9" align="center"><b>28</b></entry></row><row><entry namest="col1" nameend="col1" align="left">G2S1</entry><entry namest="col2" nameend="col2" align="center">0.0</entry><entry namest="col3" nameend="col3" align="center">1.2</entry><entry namest="col4" nameend="col4" align="center">nd</entry><entry namest="col5" nameend="col5" align="center">3.0</entry><entry namest="col6" nameend="col6" align="center">0.0</entry><entry namest="col7" nameend="col7" align="center">0</entry><entry namest="col8" nameend="col8" align="center">0</entry><entry namest="col9" nameend="col9" /></row><row><entry namest="col1" nameend="col1" align="left">G1S1FB</entry><entry namest="col2" nameend="col2" /><entry namest="col3" nameend="col3" /><entry namest="col4" nameend="col4" /><entry namest="col5" nameend="col5" /><entry namest="col6" nameend="col6" /><entry namest="col7" nameend="col7" /><entry namest="col8" nameend="col8" /><entry namest="col9" nameend="col9" align="center">6.2</entry></row><row><entry namest="col1" nameend="col1" align="left">G1S1F</entry><entry namest="col2" nameend="col2" /><entry namest="col3" nameend="col3" /><entry namest="col4" nameend="col4" /><entry namest="col5" nameend="col5" /><entry namest="col6" nameend="col6" /><entry namest="col7" nameend="col7" /><entry namest="col8" nameend="col8" /><entry namest="col9" nameend="col9" align="center">1.7</entry></row><row><entry namest="col1" nameend="col1" align="left">G2F</entry><entry namest="col2" nameend="col2" align="center">3.9</entry><entry namest="col3" nameend="col3" align="center">5.0</entry><entry namest="col4" nameend="col4" align="center">3.0</entry><entry namest="col5" nameend="col5" align="center">10.3</entry><entry namest="col6" nameend="col6" align="center">11.6</entry><entry namest="col7" nameend="col7" align="center">16.9</entry><entry namest="col8" nameend="col8" align="center"><b>22.1</b></entry><entry namest="col9" nameend="col9" align="center">4.2</entry></row><row><entry namest="col1" nameend="col1" align="left">G2</entry><entry namest="col2" nameend="col2" align="center">12.1</entry><entry namest="col3" nameend="col3" align="center">6.1</entry><entry namest="col4" nameend="col4" align="center">3.3</entry><entry namest="col5" nameend="col5" align="center">7.0</entry><entry namest="col6" nameend="col6" align="center">13.3</entry><entry namest="col7" nameend="col7" align="center">2.0</entry><entry namest="col8" nameend="col8" align="center">0.0</entry><entry namest="col9" nameend="col9" align="center">0.0</entry></row><row><entry namest="col1" nameend="col1" align="left">G1FB</entry><entry namest="col2" nameend="col2" /><entry namest="col3" nameend="col3" /><entry namest="col4" nameend="col4" /><entry namest="col5" nameend="col5" /><entry namest="col6" nameend="col6" /><entry namest="col7" nameend="col7" /><entry namest="col8" nameend="col8" /><entry namest="col9" nameend="col9" align="center"><b>25.7</b></entry></row><row><entry namest="col1" nameend="col1" align="left">G1F</entry><entry namest="col2" nameend="col2" align="center">17.4</entry><entry namest="col3" nameend="col3" align="center">16.9</entry><entry namest="col4" nameend="col4" align="center">15</entry><entry namest="col5" nameend="col5" align="center"><b>24.8</b></entry><entry namest="col6" nameend="col6" align="center"><b>22.1</b></entry><entry namest="col7" nameend="col7" align="center">16.1</entry><entry namest="col8" nameend="col8" align="center">21.5</entry><entry namest="col9" nameend="col9" align="center">12.4</entry></row><row><entry namest="col1" nameend="col1" align="left">G1</entry><entry namest="col2" nameend="col2" align="center"><b>26.1</b></entry><entry namest="col3" nameend="col3" align="center">11.3</entry><entry namest="col4" nameend="col4" align="center"><b>21.0</b></entry><entry namest="col5" nameend="col5" align="center"><b>22.2</b></entry><entry namest="col6" nameend="col6" align="center"><b>22.8</b></entry><entry namest="col7" nameend="col7" align="center">0.0</entry><entry namest="col8" nameend="col8" align="center">0.0</entry><entry namest="col9" nameend="col9" align="center">0.0</entry></row><row><entry namest="col1" nameend="col1" align="left">G0F</entry><entry namest="col2" nameend="col2" align="center">12.1</entry><entry namest="col3" nameend="col3" align="center"><b>23.1</b></entry><entry namest="col4" nameend="col4" align="center">19.4</entry><entry namest="col5" nameend="col5" align="center">5.6</entry><entry namest="col6" nameend="col6" align="center">10.5</entry><entry namest="col7" nameend="col7" align="center">1.7</entry><entry namest="col8" nameend="col8" align="center">3.0</entry><entry namest="col9" nameend="col9" align="center">0.0</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">G0</entry><entry namest="col2" nameend="col2" align="center"><b>29.1</b></entry><entry namest="col3" nameend="col3" align="center"><b>32.7</b></entry><entry namest="col4" nameend="col4" align="center"><b>38.5</b></entry><entry namest="col5" nameend="col5" align="center">15.8</entry><entry namest="col6" nameend="col6" align="center">17.7</entry><entry namest="col7" nameend="col7" align="center">13.6</entry><entry namest="col8" nameend="col8" align="center">13.9</entry><entry namest="col9" nameend="col9" align="center">0.5</entry></row></tbody></tgroup></table></tables>

An alternative for specifically targeting FcγRIII is the preparation of high mannose type antibodies.

In another aspect, the invention relates to an antibody-producing cell mentioned above. It may be a hybridoma, especially a hetero-hybridoma obtained with the fusion partner K6H6-B5 (ATCC No. CRL 1823); or an animal or human cell transfected with a vector comprising the gene coding for said antibody, in particular a cell derived from the Vero lines (ATCC No. CCL 81), YB2 / 0 (ATCC No. CRL 1662) or CHO Lec-1 (ATCC No. CRL 1735). These cells correspond to the cell lines selected by the method according to the invention, said cells producing antibodies having the characteristics mentioned above.

A preferred antibody according to the invention shows a significant biological activity (greater than or equal to that of the reference anti-Rh (D) polyclonal antibody) in the ADCC test using FcγRIII positive effector cells. Its ability to activate FcγRIII receptors (after fixation) is confirmed on models <i>in vitro</i> that highlight the modification of intracellular calcium flux, the phosphorylation of activation signal transduction molecules or the release of chemical mediators. These properties are associated with a particular structure of the oligosaccharides of the N-glycosylation site of the Fc portion of the antibody: presence of short chains, weakly galactosylated, unsilylated, having end mannoses and / or non-intermediate terminal GIcNAc for example. This antibody has therapeutic applications: prevention of the MHNN, treatment of the ITP in individuals Rh (D) positive, and any other application concerned by the use of anti-D polyclonal immunoglobulins. A preferred antibody according to the invention may also have a specificity other than anti-Rh (D) (anti-cancer cell for example). It may possess the properties described above (functional activity dependent on a mechanism of attachment / activation at the FcγRIII receptors, particular oligosaccharide structure) and be used in the immunotherapy of cancers or any other pathology for which can be performed a curative or preventive treatment using a monoclonal antibody whose mechanism of action corresponds to a functional activity via the FcγRIII receptor.

Another aspect relates to a pharmaceutical composition comprising an antibody according to the invention and the use of said antibody for the manufacture of a medicament.

Preferably, the invention relates to the use of an anti-Rh (D) antibody described above for the manufacture of a medicament intended for the prevention of Rh negative alloimmunization of Rh negative individuals. The mode of action of anti-D immunoglobulins<i>in vivo</i> is a specific binding of antibodies to the Rh (D) positive red blood cell D antigen, followed by removal of these red blood cells from the circulation mainly at the level of the spleen. This clearance is associated with a dynamic mechanism of suppression of the primary immune response in individuals and thus prevents immunization. So, an antibody of the invention can be used in a prophylactic manner for the prevention of the alloimmunization of a Rh-negative woman, immediately after the birth of a Rh-positive child, and to prevent, in subsequent pregnancies, haemolytic disease of the newborn (MHNN); during abortions, of ectopic pregnancies in cases of incompatibility Rhesus D or during transplacental hemorrhages resulting from amniocentesis, chorionic biopsies, or traumatic obstetric manipulations in situations of Rh incompatibility. In addition, an antibody of the invention may be used in the case of Rh transfusions incompatible with blood or labile blood derivatives.

The invention also relates to the use of an antibody of the invention for the manufacture of a medicament for therapeutic use in Idiopathic Thrombocytopenic Purpura (ITP). The antibodies of the invention are also useful for the manufacture of a medicament for the treatment of cancers by immunotherapy or for the treatment of infections caused by viral or bacterial pathogens.

A complementary aspect of the invention relates to the use of said antibodies, in particular for the diagnosis. The invention therefore relates to a kit comprising an antibody described above.

For the remainder of the description, reference will be made to the legends of the figures presented below.

legends

<ul id="ul0006" list-style="none" compact="compact"><li><b>Figure 1: ADCC evaluation of F60 and T125 YB2 / 0 (R270)</b>This figure represents the percentage of lysis obtained as a function of the concentration of antibodies in the presence of 100 and 500 μg / well of TEGELINE ™ (LFB, France). A high percentage of lysis is obtained for the antibodies according to the invention F60 and T125.</li><li><b>Figure 2: binding of anti-D to the receptor (FcγRIII)</b>A strong binding index is obtained for the antibodies according to the invention F60 and T125.</li><li><b>Figure 3: Construction of the T125-H26 expression vector for expression of the T125 H-chain.</b></li><li><b>Figure 4: Construction of the expression vector T125-K47 for the expression of the L chain of T125</b></li><li><b>Figure 5: Construction of the T125-IG24 expression vector for the expression of the T125 whole antibody.</b></li><li><b>Figure 6: ADCC inhibition in the presence of anti Fc RIII (CD16)</b>The ADCC test is established according to the procedure described in §3.3 in the presence of commercial anti-CD16 3G8 (TEBU) whose action is to block the FcRIII receptors present on the effector cells. The final concentration of 3G8 is 5 μg / well (25 μg / ml). A cookie is done in parallel in the absence of 3G8. The three antibodies tested are Poly-D WinRho, the antibody F60 (Pf 155 99/47) obtained according to the method described in Example I and R297 (Pf 210 01/76) obtained according to the method described in Example II.<b>Results:</b> inhibition is observed in the presence of 3G8, demonstrating that the ADCC induced by the three antibodies tested is mainly dependent on FcRIII. A slightly stronger inhibition is observed in the presence of Poly-D WinRho (83% compared to 68% and 61% inhibition for F60 and R297 respectively). This difference may be due to the presence in Poly-D of non-anti-D human IgG that will inhibit type 1 receptors (FCRI or CD64) and thus act synergistically with anti-CD16.</li><li><b>Figure 7: Characterization of Anti-D Glycans by Mass Spectrometry (MS).</b></li><li><b>Figure 8: Comparison of the MS spectra of R 290 and DF5.</b></li><li><b>Figure 9: Study of the glycosylation of D31DMM Anti-D by MS.</b></li></ul>

EXAMPLE 1 ESTABLISHMENT OF A HETEROHYBRID CELL LINE PRODUCING AN ANTI-RH (D) ANTIBODY

1-

<b>Obtaining lymphoblastoid clones and heterohybrids:</b>

<b>1.1- Source of lymphocytes:</b>

The B-cell donor is selected from plasmapheresis anti-Rh (D) donors on the activity of its anti-Rh (D) serum antibodies in the ADCC activity test described in §33. After a donation of whole blood in 1998, the "buffy coat" fraction (leucocyte concentrate) is recovered.

<b>1.2-Immortalization of donor B lymphocytes</b>

The mononuclear cells of the peripheral blood are separated from the other elements by centrifugation on Ficoll Plus (Pharmacia). They are then diluted to 10⁶ cells / ml in IMDM containing 20% ​​(v / v) fetal calf serum (FCS), to which are added 20% culture supernatant of the B95-8 line (ATCC-CRL1612), 0.1 μg / ml of cyclosporin A (Sandoz), 50 μg / ml gentamycin sulfate (Life Technologies), and divided into 24-well plates (P24 Greiner) or 96-well round-bottom plates. They are then placed in an incubator at 37 ° C, 7% CO2. After 3 weeks, the presence of anti-Rh (D) antibodies is sought by ADCC<ul id="ul0007" list-style="none" compact="compact"><li>→ Each of the 16 microwells of a positive P24 plate well is transferred to a new P24 well. This enrichment is repeated after 10 to 15 days of culture and each microwell is amplified in P96 and P24.</li><li>→ Positive P96 wells are taken up and amplified in flat-bottomed P24 (Nunc). After a few days of culture, the presence of anti-Rh (D) antibodies is sought by ADCC.</li></ul>

<b>1.3- Immune rosette enrichment (RI):</b>

The cells from one or more wells of P24 are enriched in specific cells by formation and separation of rosettes with papain-positive Rh (D) red blood cells: 1 volume of red blood cells washed in 0.9% NaCl is incubated for 10 minutes at 37 minutes. ° C with 1 volume of papain solution (Merck) at 1/1000^th (m / v), then washed 3 times with 0.9% NaCl. The cells are then washed once in Hanks solution, suspended in FCS and mixed with papain erythrocytes in the ratio of one cell to 33 red blood cells. The mixture is placed in a conical bottom centrifuge tube, centrifuged for 5 minutes at 80 g and incubated for one hour in melting ice. The mixture is then gently stirred and the Ficoll deposited at the bottom of the tube for separation for 20 minutes at 900 g. The pellet containing the rosettes is hemolyzed in NH solution₄CI for 5 minutes and the cells cultured in P24 containing irradiated human mononuclear cells. After about 1 week, the supernatants are evaluated in CELA tests (paragraph 3.2) and ADCC for the presence of anti-Rh (D) antibodies having a good activity. A new enrichment cycle is performed if the percentage of rosetting cells increases significantly compared to the previous cycle.

<b>1.4-Cloning of lymphoblastoid cells:</b>

The RI-enriched cells are divided into 5 and 0.5 cells per well in 96-well round bottom plates containing irradiated human mononuclear cells.

After approximately 4 weeks of culture, the supernatants of the wells containing cell clusters are evaluated by ADCC test.

<b>1.5- Heterofusion:</b>

The cloning wells of the EBV transformed cells exhibiting an interesting ADCC activity are amplified in culture and then fused with the heteromyeloma K6H6-B5 (ATCC CRL-1823) according to the standard PEG technique. After fusion, the cells are distributed at a rate of 2⁴ cells / well in flat-bottomed P96 containing murine intraperitoneal macrophages and in a selective medium containing aminopterin and ouabain (Sigma). After 3 to 4 weeks of culture, the supernatants of the wells containing cell clusters are evaluated by ADCC test.

<b>1.6- cloning of heterohydroids:</b>

Limit dilution cloning was performed at 4, 2 and 1 cells / well in flat-bottomed P96s. After 2 weeks, the microscopic appearance of the wells is examined to identify unique clones and then the medium is renewed. After about 2 weeks, the supernatants of the wells containing cell clusters are evaluated by ADCC test.

2-

<b>History of the clones retained:</b>

<b>2.1- Clone Producing an IgG1</b>

The EBV transformation of the d13 donor cells allowed the selection of a well, designated T125 2A2 on which were successively carried out: 2 enrichments, 3 cycles of RI, and cloning at 5 cells / well to give 2 clones:<ul id="ul0008" list-style="none" compact="compact"><li>1) T125 2A2 (5/1) A2 from which the DNA was extracted for the preparation of the recombinant vector;</li><li>2) T125 (5/1) A2 which was fused with K6H6-B5 to give F60 2F6 then after 5 clones F60 2F6 (5) 4C4, clone retained for the constitution of a cell stock prior to the preparation of libraries.</li></ul>

It is an IgG1 possessing a Kappa light chain.<img file="EP1518864A2_D0002.tif" />

<b>2.2- Clone Producing an IgG3</b>

According to the same method as that used for the preparation of the IgG1 isotype antibody, an IgG3 producing line was prepared. The original cells come from a whole blood donation, from another designated donor, whose "buffy coat" fraction (leukocyte concentrate) was recovered. It is an IgG3 with a Kappa light chain.<img file="EP1518864A2_D0003.tif" /><img file="EP1518864A2_D0004.tif" />

3-

<b>Methods of Evaluating Anti-Rh (D) Antibodies:</b>

After purification by affinity chromatography on Protein A Sepharose (Pharmacia) and dialysis in 25mM Tris buffer, 150mM NaCl, pH 7.4, the concentration of the T125 antibody is determined by ELISA technique. In vitro biological activity is then measured by the ADCC technique.

<b>3.1- Determination of the IgG level and the isotypes by ELISA technique:</b>

<ul id="ul0009" list-style="bullet" compact="compact"><li><i>Total IgG</i>Coating: anti-IgG (Calbiochem) at 2μg / ml in 0.05M carbonate buffer pH 9.5, overnight at 4 ° C. Saturation: dilution buffer (PBS + 1% BSA + 0.05% Tween 20, pH 7.2) 1h at room temperature. Wash (repeat at each step): H2O + 150mM NaCl + 0.05% Tween 20. Dilution of the samples in dilution buffer at about 100 ng / ml and the control range consisting of polyvalent human IgG LFB prediluted at 100 ng / ml. Incubation 2h at room temperature. Conjugate: anti-IgG (Diagnostic Pasteur) diluted 1/5000, 2 hours at room temperature. Substrate: OPD at 0.5 mg / ml (sigma) in phosphate citrate buffer, Na perborate (Sigma), 10 minutes at oscillation. Stopping the reaction with 1N HCl and reading at 492 nm.</li><li><i>Dosage Kappa chain.</i>Coating: anti-Kappa (Caltag Lab) at 5μg / ml in 0.05M carbonate buffer pH 9.5.1 overnight at 4 ° C. Saturation: dilution buffer (PBS + 1% BSA + 0.05% Tween 20, pH 7.2) 1h at room temperature. Wash (repeat at each step): H2O + 150mM NaCl + 0.05% Tween 20. Dilution of the samples in dilution buffer at about 100 ng / ml and the control range consisting of the monoclonal antibody AD3T1 LFB (Kappa / gamma 3) prediluted at 100 ng / ml. Incubation 2 hours at room temperature Conjugate: biotinylated anti-kappa (Pierce) diluted 1/1000 in the presence of streptavidin-peroxidase (Pierce) diluted 1/1500, 2 hours at room temperature. Substrate: OPD at 0.5 mg / ml (sigma) in phosphate citrate buffer, Na perborate (Sigma), 10 minutes in the dark. Stopping the reaction with 1N HCl and reading at 492 nm.</li></ul>

<b>3.2- Specific anti-D assay by CELA technique (Cellular Enzyme Linked Assay):</b>

This method is used for the specific assay of anti-D antibodies especially when it is culture supernatant at culture stages where other non-anti-D immunoglobulins are present in the solution (early steps after EBV transformation) .<u>Principle:</u> the anti-D antibody is incubated with Rhesus positive red cells and then revealed by an anti-human Ig labeled with alkaline phosphatase. 100 μl of 10% Rh + red cells diluted in 1% Liss-BSA dilution buffer. Dilution of samples in dilution buffer at about 500 ng / ml and the control range consisting of a purified monoclonal human anti-D IgG (DF5, LFB) prediluted at 500 ng / ml. Incubation 45 min at room temperature. Wash (renew at each step): H2O + 150mM NaCl. Conjugate: Anti-Alkaline IgG phosphatase (Jackson) diluted 1/4000 in PBS + 1% BSA, 1h30 at room temperature. Substrate: PNPP at 1mg / ml (sigma) to 1M diethanolamine, 0.5mM MgCl2; PH 9.8. Stopping the reaction with 1N NaOH and reading at 405 nm.

<b>3.3- ADCC technique</b>

The Antibody-Dependent Cellular Cytotoxicity (ADCC) technique is used to evaluate the ability of antibodies (anti-D) to induce lysis of Rh-positive red blood cells in the presence of effector cells (mononuclear cells or lymphocytes). Briefly, the red blood cell packed red cells are treated with papain (1 mg / ml, 10 min at 37 ° C) and washed in 0.9% NaCl. The effector cells are isolated from a pool of at least 3 buffy coat, by centrifugation on Ficoll (Pharmacia), followed by an adhesion step in the presence of 25% FCS, so as to obtain a ratio lymphocytes / monocytes of the order of 9. In a microtitre plate (96 wells) was deposited per well: 100 .mu.l of purified anti-D antibody at 200 ng / ml, 25 .mu.l of Rh + papainous red cells (ie 1x10⁶), 25μl of effector cells (ie 2x10⁶) and 50 μl of polyvalent IgG (Tegelin LFB for example) at the usual concentrations of 10 and 2 mg / ml. Dilutions are made in IMDM 0.25% FCS. After incubation for one night at 37 ° C., the plates are centrifuged and the hemoglobin released into the supernatant is measured in the presence of a substrate specific for peroxidase activity (2.7 diaminofluorene, DAF). The results are expressed as a percentage of lysis, 100% corresponding to the total lysis of the red blood cells to NH4Cl (100% control), and 0% to the reaction mixture without antibodies (control 0%). The specific lysis is calculated as a percentage according to the following formula:<maths id="math0001" num=""><math display="block"><mrow><mfrac><mrow><mtext>(DO sample - DO witness 0%) x 100 </mtext></mrow><mrow><mtext>100% control OD - 0% control OD</mtext></mrow></mfrac><mtext> =% ADCC</mtext></mrow></math><img file="EP1518864A2_D0005.tif" /></maths>

The results presented in FIG. 1 show the activity of the antibody produced by the F60 heterohybrid compared to those of the reference antibodies:<ul id="ul0010" list-style="dash" compact="compact"><li>polyclonal antibodies to Rh (D) POLY-D LFB 51 and WinRhO W03 (Cangene) = positive controls</li><li>monoclonal antibody DF5 (inactive <i>in vivo</i> on the clearance of Rh (D) positive RBCs (BROSSARD / FNTS, 1990, unpublished)) = negative control</li><li>purified IgG1 (separated from IgG3) from the WinRhO W03 polyclonal.</li></ul> Two concentrations of human IgG (Tegelin LFB) are used to show that the inhibition of negative control activity is related to the binding of competing IgG to Fcγ type I receptors.

<b>3.4- FcγRIII fixation technique (CD16):</b>

This test makes it possible to assess the binding of anti-Rh (D) antibodies of IgG1 isotype on FcγRIII and in particular to differentiate IgG3 antibodies. Given the low affinity of this receptor for monomeric IgG, the prior binding of the antibodies to the D antigen is necessary.<u>Principle:</u> on membranes Rh + coated microtitration plate, the antibody to be tested (anti-D) and then transfected Jurkat cells expressing on their surface FcγRIII receptor. After centrifugation, the "Rh + / anti-D / Jurkat CD16 membrane" interaction is visualized by a homogeneous spread of Jurkat CD16 in the well. In contrast, the cells cluster in the center of the well in the absence of interaction. The intensity of the reaction is expressed in numbers of +.<u>Method:</u> 1) Incubation for 1 hour at 37 ° C. of the anti-D antibody (50 μl at 1 μg / ml in IMDM) on Capture R plate (Immunochim), followed by washing with water + NaCl 0.9%. Addition of Jurkat CD16 (2.10⁶ cells / ml) in IMDM + 10% FCS. Incubation 20 min at 37 ° C followed by centrifugation and evaluation of cell adhesion (against a control range). 2) Revelation of anti-D fixed on Capture R plates by ELISA technique using anti-human IgG-Peroxidase at 1/5000 (Sanofi Diagnostics Pasteur) after lysing Jurkat CD16 cells with Tris 0.2M HCl, 6M Urea, pH 5.3-5.5. OPD revelation then reading of the optical density (OD) at 492 nm. Expression of the results: we assign an arbitrary value of 0 to 3 depending on the fixation and spreading of Jurkat CD16 cells. These values ​​are assigned to each defined OD interval (0.1 to 0.1). We trace:<ul id="ul0011" list-style="none" compact="compact"><li>* a curve: adhesion of Jurkat cells (Y) as a function of the amount of anti-D fixed on the membranes of red blood cells (X).</li><li>* or a histogram of the corresponding "fixation indices" for each antibody, to the sum of each Jurkat cell binding value (0 to 3) affected per OD interval (on a portion common to all the antibodies tested).</li></ul> An example of a histogram is shown in Figure 2. Anti-Rh (D) antibodies of IgG1 isotype (F60 and T125 YB2 / 0) show a binding index close to that of polyclonal IgG1 (WinRho), whereas the negative control antibodies DF5 and AD1 do not bind. In the same way, the IgG3 isotype antibody (F41) has a good binding index, slightly lower than that of IgG3 purified from the Winrho polyclonal and higher than that of the AD3 antibody (another IgG3 tested and ineffective in clinical trial, mixed with AD1 (Biotest / LFB, 1997, unpublished).

<b>Example 2</b>

<b>PRODUCTION OF RECOMBINANT ANTI-D (AN) ANTIBODY</b>

1- Isolation and amplification of the cDNAs encoding the heavy and light chains of Ac

<b>1.1- RNA extraction and cDNA synthesis</b>

The total RNAs were extracted from an anti-D (IgG G1 / Kappa) producing clone obtained by EBV transformation: T125 A2 (5/1) A2 (see paragraph 2, example 1). The corresponding cDNAs were synthesized by reverse transcription of the total RNAs using oligo dT primers.

<b>1.2- Amplification of the variable region of the T125-A2 heavy chain: VH sequence</b>

/

<b>T125-A2</b>

The VH / T125-A2 sequence is obtained by amplification of the cDNAs of T125-A2 using the following primers:<ul id="ul0012" list-style="dash" compact="compact"><li>A2VH5 primer located at 5 'of the leader region of the VH gene of T125-A2, introduces a consensus leader sequence (in bold) deduced from leader sequences already published and associated with VH genes belonging to the same VH3-30 family as the gene VH of T125-A2; this sequence also contains an Eco RI restriction site (in italics) and a Kozak sequence (underlined):<img file="EP1518864A2_D0006.tif" /></li><li>antisense primer GSP2ANP located 5 'of the constant region (CH) of T125-A2:<img file="EP1518864A2_D0007.tif" /></li></ul>

<b>1.3- Amplification of the constant region of T125 A2: CH sequence</b>

/

<b>T115-A2</b>

The CH / T125-A2 sequence is obtained by amplification of the cDNAs of T125-A2 using the following primers:<ul id="ul0013" list-style="dash" compact="compact"><li>G1 primer localized 5 'of the CH region of T125-A2:<img file="EP1518864A2_D0008.tif" /> The first G base of the CH sequence is here replaced by a C (underlined) in order to recreate an Eco RI site after cloning (see section 2.1.1).</li><li>H3'Xba antisense primer located 3 'of the CH of T125-A2, introduces an Xba I site (underlined) 3' of the amplified sequence:<img file="EP1518864A2_D0009.tif" /></li></ul>

<b>1.4- Amplification of the Kappa light chain: sequence K</b>

/

<b>T125-A2</b>

The entire Kappa chain of T125-A2 (K / T125-A2 sequence) is amplified from the T125-A2 cDNAs using the following primers:<ul id="ul0014" list-style="dash" compact="compact"><li>A2VK3 primer located 5 'of the leader region of the VK gene of T125-A2, introduces a consensus sequence (in bold) deduced from the sequence of several leader regions of VK VH genes belonging to the same VK1 subgroup as the VK gene of T125-A2; this sequence also contains an Eco RI restriction site (in italics) and a Kozak sequence (underlined):<img file="EP1518864A2_D0010.tif" /></li><li>antisense KSE1 primer localized in 3 'of Kappa, introduces an Eco RI site (underlined):<img file="EP1518864A2_D0011.tif" /></li></ul>

Fig. 1 schematizes the amplification strategies of heavy and light chains of T125-A2.

2- Construction of the expression vectors

<b>2.1- T125-A2 heavy chain expression vector: T125 H26</b>

The construction of T125-H26 is summarized in FIG. 2. It is carried out in two stages: firstly, the construction of the V51-CH / T125-A2 intermediate vector by insertion of the T125-A2 constant region into the pICI-neo derived V51 expression vector (FIG. 3) then cloning of the variable region in V51-CH / T125-A2.

2.1.1 cloning of the constant region of T125-A2

The amplified CH / T125-A2 sequence is inserted after phosphorylation at the Eco RI site of vector V51 (Fig. 3). The ligation is carried out after prior treatment with the Klenow polymerase of the Eco RI cohesive ends of V51 in order to make them "free ends". The primer G1 used for the amplification of CH / T125-A2 makes it possible to recreate, after its insertion in V51, a 5 'Eco RI site of CH / T125-A2.

2.1.2 variable region cloning of T125-A2

The VH / T125-A2 sequence obtained by amplification is digested with Eco RI and Apa I and then inserted at the Eco RI and Apa I sites of the V51-G1 / T125-A2 vector.

<b>2.2- Vector light chain of T125-A2: T125 K47</b>

The construction of T125-K47 is shown in Fig.4. The K / T125-A2 sequence obtained by PCR is digested with Eco RI and inserted at the Eco RI site of the pICI-neo derived V47 expression vector (Fig. 5).

<b>2.3- T125-A2 heavy and light chain vector: T125-IG24</b>

The construction of T125-IG24 is shown schematically Fig.6. This vector which contains the two T125-A2 heavy and kappa chain transcription units is obtained by insertion of the SalI-Xho I fragment of T125-K47 containing the K / T125-A2 transcription unit at the Xho I sites. and Sal Ide T125-H26. Thus heavy and light chains of T125-A2 are expressed under the control of the CMV promoter; other promoters can be used: RSV, IgG heavy chain promoter, MMLV LTR, HIV, β actin, etc.

<b>2.4- T125 A2 heavy and light chain specific leader vector: T125-LS4</b>

A second T125-A2 expression vector is also constructed in which the consensus leader sequence of the Kappa chain is replaced by the actual sequence of the T125-A2 leader region previously determined by sequencing "5'-RACE PCR products. (Rapid Amplification of cDNA 5 'Ends). The construction of this T125-LS4 vector is described in FIG. 7. It is carried out in two steps: firstly the construction of a new Kappa chain expression vector of T125-A2, T125-KLS18, then the assembly of the final expression vector, T125-LS4, containing the two modified light chain and heavy chain transcription units.

2.4.1 construction of the vector T125-KLS18

The 5 'part of the Kappa consensus leader sequence of the T125-K47 vector is replaced by the T125 specific leader sequence (KLS / T125-A2) during an amplification step of the K / T125-A2 sequence carried out at using the following primers:<ul id="ul0015" list-style="dash" compact="compact"><li>primer A2VK9, modifies the 5 'part of the leader region (in bold) and introduces an Eco RI site (underlined) as well as a Kozak sequence (in italics):<img file="EP1518864A2_D0012.tif" /></li><li>KSE1 primer (described in section 1.4)</li></ul>

The T125-KLS18 vector is then obtained by replacing the T125-K47 Eco RI fragment containing the original K / T125-A2 sequence with the new EcoRI-digested KLS / T125-A2 sequence.

2.4.2 construction of the final vector T125-LS4

The Sal I - Xho I fragment of T125-KLS18 containing the modified KLS / T125-A2 sequence is inserted into T125-H26 at the Xho I and Sal I sites.

3- Production of anti-D Ab in the YB2 / 0 line

<b>3.1- Without gene amplification</b>

Both T125-IG24 and T125-LS4 expression vectors were used for transfection of cells of the YB2 / 0 line (rat myeloma, ATCC line No. 1662). After transfection by electroporation and selection of transformants in the presence of G418 (neo selection) several clones were isolated. The production of recombinant anti-D Ab is approximately 0.2 μg / 10⁶ cells / 24h (<i>value obtained for clone 3B2 of R270</i>). The ADCC activity of this recombinant Ac is greater than or equal to that of the poly-D controls (<b>figure 1</b>). The products produced using the two expression vectors are not significantly different in terms of production level or ADCC activity.

<b>3.2- With gene amplification</b>

The gene amplification system used is based on the selection of transformants resistant to methotrexate (MTX). It requires the prior introduction of a transcription unit coding for the DHFR enzyme (dihydrofolate reductase) in the recombinant Ac expression vector (SHITARI et al., 1994).

3.2.1 construction of the T125-dhfr expression vector 13

The diagram shown in Fig. 8 describes the construction of the T125-A2 expression vector containing the murine dhfr gene. A first vector (V64) was constructed from a vector derived from pCI-neo, V43 (Fig. 9), replacing, in 3 'of the SV40 promoter and in 5' of a synthetic polyadenylation sequence, the neo gene (HindIII-Csp 45 I fragment) by the cDNA of the murine dhfr gene (obtained by amplification from plasmid pMT2). This vector is then modified to create a 5 'Cla I site of the dhfr transcription unit. The Cla I fragment containing the dhfr transcription unit is then inserted at the Cla I site of T125-LS4.

3.2.2 selection in the presence of MTX

<ul id="ul0016" list-style="none" compact="compact"><li>◆ 1^era strategy:<ul id="ul0017" list-style="none" compact="compact"><li>The YB2 / 0 cells transfected by electroporation with the T125-dhfr13 vector are selected in the presence of G418. Transformants producing recombinant Ac are then subjected to selection in the presence of increasing doses of MTX (from 25nM to 25μM). The evolution of recombinant Ac production, a control of the gene amplification process, is followed during the selection steps in MTX. MTX-resistant transformants are then cloned by limiting dilution. The level and stability of recombinant Ac production is evaluated for each clone obtained. The productivity of anti-D antibodies after gene amplification is approximately 13 (+/- 7) μg / 10⁶cells / 24 h.</li></ul></li><li>◆ 2^th strategy:<ul id="ul0018" list-style="none" compact="compact"><li>YB2 / 0 cells transfected by electroporation with T125-dhfr13 vector are selected in the presence of G418. The best transformants producing recombinant Ac are cloned by limiting dilution before selection in the presence of increasing doses of MTX. The evolution of the production of each clone, a control of the gene amplification process, is followed during the selection steps in MTX. The level and stability of recombinant Ac production is evaluated for each MTX-resistant clone obtained.</li></ul></li></ul>

<b>4- Evaluation of the activity of the T125 antibody expressed in YB2</b>

/

<b>0</b>

After purification by affinity chromatography on Protein A Sepharose (Pharmacia) and dialysis in 25mM Tris buffer, 150mM NaCl, pH 7.4, the concentration of the T125 antibody is determined by ELISA technique. In vitro biological activity is then measured by the previously described ADCC test. The results are shown in Figure 1.

<b>EXAMPLE 3: EVIDENCE OF THE RELATION BETWEEN GLYCANNIC STRUCTURE AND DEPENDENT ACTIVITY OF FCγRIII</b>

<b>1- Cell culture in the presence of Deoxymannojirimycin (DMM).</b>

Several studies describe the effect of enzymatic inhibitors on the glycosylation of immunoglobulins and on their biological activity. An increase in ADCC activity is reported by ROTHMAN et al. 1989, an increase not attributable to an improvement in the affinity of the antibody for its target. The modification of glycosylation caused by the addition of DMM consists of an inhibition of α1,2 mannosidase I present in the Golgi. It leads to the production of a larger proportion of polymannosylated, non-fucosylated structures. Different lines producing anti-Rh (D) antibodies were placed in the presence of DMM and the functional activity of the monoclonal antibodies produced was evaluated in the form of culture supernatants or after purification. Cells (hetero-hybrid or lymphoblastoid) are seeded between 1 and 3x10⁵ cells / ml, and cultured in IMDM culture medium (Life Technologies) with 10% FCS and in the presence of 20 μg / ml of DMM (Sigma, Boehringer). After 3 medium changes, the culture supernatants are tested by human IgG ELISA and then by ADCC.<tables id="tabl0002" num="0002"><table frame="all"><title>Table 2:</title><tgroup cols="4" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="39.37mm" /><colspec colnum="2" colname="col2" colwidth="39.37mm" /><colspec colnum="3" colname="col3" colwidth="39.37mm" /><colspec colnum="4" colname="col4" colwidth="39.37mm" /><thead valign="top"><row><entry namest="col1" nameend="col4" align="center">Effect of culture in the presence of DMM on ADCC activity of different anti-Rh (D)</entry></row><row><entry namest="col1" nameend="col1" rowsep="0" align="center">Samples</entry><entry namest="col2" nameend="col3" align="center">ADCC activity As% of poly-D activity LFB51</entry><entry namest="col4" nameend="col4" rowsep="0" align="center">Minimum dose of DMM required μg / ml</entry></row><row><entry namest="col1" nameend="col1" /><entry namest="col2" nameend="col2" align="center">Culture without DMM</entry><entry namest="col3" nameend="col3" align="center">Culture in the presence of DMM</entry><entry namest="col4" nameend="col4" /></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="center">F60</entry><entry namest="col2" nameend="col2" align="center">109</entry><entry namest="col3" nameend="col3" align="center">113</entry><entry namest="col4" nameend="col4" align="center">NT</entry></row><row><entry namest="col1" nameend="col1" align="center">D31</entry><entry namest="col2" nameend="col2" align="center">19</entry><entry namest="col3" nameend="col3" align="center">87</entry><entry namest="col4" nameend="col4" align="center">10</entry></row><row><entry namest="col1" nameend="col1" align="center">DF5</entry><entry namest="col2" nameend="col2" align="center">26</entry><entry namest="col3" nameend="col3" align="center">62</entry><entry namest="col4" nameend="col4" align="center">20</entry></row><row><entry namest="col1" nameend="col1" align="center">T125 RI (3)</entry><entry namest="col2" nameend="col2" align="center">3</entry><entry namest="col3" nameend="col3" align="center">72</entry><entry namest="col4" nameend="col4" align="center">20</entry></row><row><entry namest="col1" nameend="col1" align="center">T125-CHO</entry><entry namest="col2" nameend="col2" align="center">0</entry><entry namest="col3" nameend="col3" align="center">105</entry><entry namest="col4" nameend="col4" align="center">5</entry></row><row rowsep="1"><entry namest="col1" nameend="col4" align="justify"><u>NT = not tested</u></entry></row></tbody></tgroup></table></tables>• The culture in the presence of Deoxymannojirimycin (DMM) brings a significant improvement of the ADCC results for the weakly active antibodies previously produced by: <tables id="tabl0003" num="0003"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">A human-mouse hybridoma</entry><entry namest="col2" nameend="col2" align="left">D31</entry></row><row><entry namest="col1" nameend="col1" align="left">A human lymphoblastoid line</entry><entry namest="col2" nameend="col2" align="left">DF5</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">A transfected murine line</entry><entry namest="col2" nameend="col2" align="left">T125 in CHO</entry></row></tbody></tgroup></table></tables>• The addition of DMM can restore the ADCC activity of an antibody derived from clone T125 = T125 RI (3) (described in Example 1) and which has lost this activity by a prolonged culture. The strong activity of the antibody produced by the F60 hetero-hybridoma (the production of which is described in Example 1) is not modified by culture in the presence of DMM.

<b>2- Production of recombinant anti-D antibodies by different cell lines:</b>

2.1 Preparation of an Expression Vector for the DF5 Antibody

The nucleotide sequence of the DF5 antibody, a negative control in the ADCC test, is used to study the transfection of this antibody in a few lines, parallel to the transfection of the T125 antibody. The sequences encoding the Ac DF5 are isolated and amplified according to the same techniques used for recombinant Ac T125-A2.<ul id="ul0019" list-style="bullet" compact="compact"><li>The corresponding cDNAs are first synthesized from total RNA extracted from the clone producing anti-D (IgG G1 / Lambda) 2MDF5 obtained by EBV transformation.</li><li>Amplification of the heavy and light chains is then carried out from these cDNAs using the primers presented below.</li><li>Amplification of the variable region of the DF5 heavy chain (VH / DF5 sequence):<ul id="ul0020" list-style="dash" compact="compact"><li>DFSVH1 primer located 5 'to the leader region (in bold) of the VH gene of DF5 (published sequence: Chouchane L et al.); this primer also contains an Eco RI restriction site (in italics) and a Kozak sequence (underlined):<img file="EP1518864A2_D0013.tif" /></li><li>antisense primer GSP2ANP located 5 'of the constant region (CH) already described in section 1.2 (example 2)</li></ul></li><li>Amplification of the constant region CH of DF5 (sequence CH / DF5): primers G1 and H3'Xba already described in paragraph 1.3 (Example 2).</li><li>DF5 Lambda light chain amplification (LBD / DF5 sequence):<ul id="ul0021" list-style="dash" compact="compact"><li>DF5VLBD1 primer located in the 5 'leading region of the DF5 VL gene, introduces a consensus sequence (in bold) deduced from the sequence of several leader regions of VL genes belonging to the same VL1 subgroup as the VL gene of 2MDF5; this sequence also contains an Eco RI restriction site (in italics) and a Kozak sequence (underlined):<img file="EP1518864A2_D0014.tif" /></li><li>LSE1 antisense primer located in 3 'of Lambda, introduces an Eco RI site (underlined):<img file="EP1518864A2_D0015.tif" /></li></ul></li><li>The construction of the heavy chain (DFS-H31), light chain (DFS-L10) and heavy and light chains (DFS-IG1) expression vectors of the Ac DF5 is carried out according to a construction scheme similar to the vectors expressing the Ac T125-A2.</li></ul>

All the original leader sequences (introduced at the level of the amplification primers) are conserved in these different vectors.

2.2- Transfection of Different Cell Lines with T125 and DF5 Antibodies

The three expression vectors T125-IG24, T125-LS4 and DF5-IgG1 are used for the transfection of cells of different lineages: Stable or transient transfections are performed by electroporation or transfection reagent. <tables id="tabl0004" num="0004"><table frame="all"><title>Table 3:</title><tgroup cols="3" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="52.50mm" /><colspec colnum="2" colname="col2" colwidth="52.50mm" /><colspec colnum="3" colname="col3" colwidth="52.50mm" /><thead valign="top"><row><entry namest="col1" nameend="col3" align="center">Cell lines used for the transfection of anti-Rh (D) antibodies</entry></row><row><entry namest="col1" nameend="col1" align="center"><b>Name</b></entry><entry namest="col2" nameend="col2" align="center"><b>Reference</b></entry><entry namest="col3" nameend="col3" align="center"><b>Cell type</b></entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="center">CHO-K1</entry><entry namest="col2" nameend="col2" align="center">ATCC CCL 61</entry><entry namest="col3" nameend="col3" align="center">Chinese hamster ovary (epithelium like)</entry></row><row><entry namest="col1" nameend="col1" align="center">CHO-Lec10</entry><entry namest="col2" nameend="col2" align="center">Fenouillet et al., 1996, Virology, 218, 224-231</entry><entry namest="col3" nameend="col3" align="center">Chinese hamster ovary (epithelium like)</entry></row><row><entry namest="col1" nameend="col1" align="center">Jurkat</entry><entry namest="col2" nameend="col2" align="center">ATCC TIB-152</entry><entry namest="col3" nameend="col3" align="center">Human T cell (Leukemia T)</entry></row><row><entry namest="col1" nameend="col1" align="center">Molt-4</entry><entry namest="col2" nameend="col2" align="center">ATCC CRL 1582</entry><entry namest="col3" nameend="col3" align="center">Human T cell (Acute lymphoblastic leukemia)</entry></row><row><entry namest="col1" nameend="col1" align="center">WIL2-NS</entry><entry namest="col2" nameend="col2" align="center">ATCC CRL 8155</entry><entry namest="col3" nameend="col3" align="center">EBV-transformed human B-cell</entry></row><row><entry namest="col1" nameend="col1" align="center">Vero</entry><entry namest="col2" nameend="col2" align="center">ATCC CCL 81</entry><entry namest="col3" nameend="col3" align="center">African green monkey kidney (fibroblast like)</entry></row><row><entry namest="col1" nameend="col1" align="center">COS-7</entry><entry namest="col2" nameend="col2" align="center">ATCC CRL 1651</entry><entry namest="col3" nameend="col3" align="center">African green monkey kidney transformed SV40 (fibroblast like)</entry></row><row><entry namest="col1" nameend="col1" align="center">HEK-293</entry><entry namest="col2" nameend="col2" align="center">ATCC CRL 1573</entry><entry namest="col3" nameend="col3" align="center">Primary Human Embryonic Kidney Transformed by DNA Adenovirus 5 Defective</entry></row><row><entry namest="col1" nameend="col1" align="center">YB2 / 0</entry><entry namest="col2" nameend="col2" align="center">ATCC CRL 1662</entry><entry namest="col3" nameend="col3" align="center">Non-secretory rat myeloma</entry></row><row><entry namest="col1" nameend="col1" align="center">BHK-21</entry><entry namest="col2" nameend="col2" align="center">ATCC CCL 10</entry><entry namest="col3" nameend="col3" align="center">Newborn hamster kidney (fibroblast like)</entry></row><row><entry namest="col1" nameend="col1" align="center">K6H6-B5</entry><entry namest="col2" nameend="col2" align="center">ATCC CRL 1823</entry><entry namest="col3" nameend="col3" align="center">non-secretory human-mouse heteromyeloma</entry></row><row><entry namest="col1" nameend="col1" align="center">NSO</entry><entry namest="col2" nameend="col2" align="center">ECACC 85110503</entry><entry namest="col3" nameend="col3" align="center">non-secretory mouse myeloma (lymphoblate like)</entry></row><row><entry namest="col1" nameend="col1" align="center">SP2 / 0- Ag 14</entry><entry namest="col2" nameend="col2" align="center">ECACC 85072401</entry><entry namest="col3" nameend="col3" align="center">Mouse hybridoma x nonsecretory mouse</entry></row><row><entry namest="col1" nameend="col1" align="center">CHO Lec-1</entry><entry namest="col2" nameend="col2" align="center">ATCC CRL 1735</entry><entry namest="col3" nameend="col3" align="center">Chinese hamster ovary</entry></row><row><entry namest="col1" nameend="col1" align="center">CHO dhfr-</entry><entry namest="col2" nameend="col2" align="center">ECACC 94060607</entry><entry namest="col3" nameend="col3" align="center">Chinese hamster ovary</entry></row><row><entry namest="col1" nameend="col1" align="center">CHO Pro-5</entry><entry namest="col2" nameend="col2" align="center">ATCC CRL 1781</entry><entry namest="col3" nameend="col3" align="center">Chinese hamster ovary</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="center">P3X63 Ag8.653</entry><entry namest="col2" nameend="col2" align="center">ATCC CRL 1580</entry><entry namest="col3" nameend="col3" align="center">Non-secretory mouse myeloma</entry></row></tbody></tgroup></table></tables>

After selection of the transformants in the presence of G418 (neo selection) several clones were isolated.

The modification of effector activity of a humanized monoclonal antibody as a function of the expression cell has been described by CROWE et al (1992), with the cell lines CHO, NSO, YB2 / O.

The results obtained here confirm the importance of the expression cell line with respect to the functional characteristics of the antibody to be produced. Among the cells tested, only the Vero, YB2 / 0 and CHO Lec-1 lines make it possible to express recombinant anti-Rh (D) monoclonal antibodies with a strong lytic activity in the ADCC test (see Example 1 and Table 3).

Table 3: ADCC activity of DF5 and T125 antibodies obtained by transfection in different cell lines. The results are expressed as a percentage of the activity of the reference polyclonal antibody: Poly-D LFB 51<tables id="tabl0005" num="0005"><img file="EP1518864A2_D0016.tif" /></tables><tables id="tabl0006" num="0006"><img file="EP1518864A2_D0017.tif" /></tables>

3- study of glycan structures

The characterization of the glycan structures of the anti-Rh-D antibody was performed on four purified products having ADCC activity (F60, and three recombinant proteins derived from T125) in comparison with two purified products that were inactive or very weakly active in the ADCC test. according to the invention (D31 and DF5). In practice, oligosaccharides are separated from the protein by specific enzymatic deglycosylation by PNGase F at Asn 297. The oligosaccharides thus released are labeled with a fluorophore, separated and identified by different complementary techniques that allow:<ul id="ul0022" list-style="dash" compact="compact"><li>A fine characterization of the glycanic structures by matrix-assisted laser desorption mass spectrometry (MALDI) by comparison of the experimental masses with the theoretical masses.</li><li>The determination of the ion exchange HPLC sialylation rate (GlycoSep C)</li><li>The separation and the quantification of the oligosaccharide forms according to criteria of hydrophilicity by HPLC in normal phase (GlycoSep N)</li><li>The separation and quantification of oligosaccharides by capillary electrophoresis with laser-induced fluorescence detection (HPCE-LIF).</li></ul>

1) Characterization of the Glycans of Active Forms

The different active forms studied are F60 and three recombinant antibodies, R 290, R 297 and R 270, derived from T125 and produced in YB2 / 0. The fine characterization of the glycanic structures by mass spectrometry (FIG. 7) shows that these forms are all of the biantennic type. In the case of R 270 the majority form is of nonfucosylated agalactosylated type (G0, mass exp. 1459.37 Da, fig 1). Three other structures are identified: fucosylated agalactosylated (G0F to 1605.41 Da), nonfucosylated monogalactosylated (G1 to 1621.26 Da) and fucosylated monogalactosylated (G1F to 1767.43 Da) minority. These same four structures are characteristic of R 290, F 60 and R 297 (Figure 1). These four antibodies active in ADCC are also characterized by the absence of oligosaccharides having a N-acetylglucosamine bisector residue. Quantification of the glycan structures by the various HPLC and HPCE-LIF techniques (Table I) confirms the presence of the four forms identified by mass: G0, G0F, G1 and G1F. The sialylation rate is very low, especially for the recombinant products, from 1 to 9.4%, which is confirmed by the similarity of the mass spectra obtained before and after enzymatic desialylation. The fucosylation rate varies from 34 to 59%.

2) Inactive forms

The different inactive forms studied are D31 and DF5. The quantification of the glycanic structures by the various chromatographic and capillary electrophoresis techniques (Table I) reveals, for these two antibodies, a sialylation rate close to 50%, and a fucosylation rate of 88 and 100% for D31 and DF5, respectively. These levels of sialylation and fucosylation are much higher than those obtained from the active forms.

The characterization of the glycanic structures shows that the majority form is, for the two antibodies, of the fucosylated bigalactosylated monosialylated biantenea type (G2S1F, Table I). Characterization by mass spectrometry of D31 (FIG. 7) reveals that the neutral forms are mainly of fucosylated monogalactosylated type (G1F at 1767.43 Da) and fucosylated bigalactosylated type (G2F at 1929.66 Da).

The inactive DF5 antibody is characterized by the presence of oligosaccharides having a spacer GIcNAc residue. In particular, the mass analysis (FIG. 8) reveals the presence of a predominant neutral form of monogalactosylated fucosylated type Bisec-GlcNAc intermediate (G1FB at 1851.03 Da). On the other hand, these structural forms are non-detectable or present in trace amounts on the active antibodies studied.

The ADCC activity of D31 after DMM action increases from 10% to 60%. The glycan structures of D31 DMM differ from those of D31 by the presence of oligomannose forms (Man 5, Man 6 and Man 7) (see Figure 9).

3) Conclusion

The different active antibodies are modified on Asn 297 by N-glycosylations of biantenné type and / or oligomanosidiques. For the biantenated forms they are very weakly sialylated short structures, weakly fucosylated, weakly galactosylated and without intermediate GlcNAc.

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