Antibody blocking human FcγRIIIA and FcγRIIIB
The present invention relates to novel antibodies, in particular murine monoclonal antibodies, chimeric and humanized, that are able to block specifically the human IgG receptors FcγRIIIA (CD16A) and FcγRIIIB (CD16B) as well as the amino and nucleic acid sequences coding for such antibodies. The invention also comprises the use of such antibodies or of fragments thereof as a medicament for the preventive and/or therapeutic treatment of diseases involving CD16, like autoimmune diseases, inflammatory disorders, allergies and infections, without inducing any adverse effects. In particular, these antibodies and fragments can prevent or treat anti-drug idiopathic thrombocytopenic purpura (ITP), rheumatoid arthritis (RA) and autoimmune hemolytic anemia (ANA).
1 . An antagonistic antibody against CD16 or an antigen-binding fragment thereof, said antibody comprising:
a) a light chain comprising a CDR-L1, CDR-L2 and CDR-L3 having respectively the amino acid sequences SEQ ID NO: 1, 2 and 3; and
b) a heavy chain comprising a CDR-H1, CDR-H2 and CDR-H3 having respectively the amino acid sequences SEQ ID NO: 4, 5 and 6.
2 . An antagonistic antibody against CD16 or an antigen-binding fragment thereof, said antibody comprising:
a) a light chain comprising a CDR-L1, CDR-L2 and CDR-L3 having respectively the amino acid sequences SEQ ID NO: 1, 2 and 3, with no more than a single amino acid change in only one of CDR-L1, CDR-L2, or CDR-L3; and
b) a heavy chain comprising a CDR-H1, CDR-H2 and CDR-H3 having respectively the amino acid sequences SEQ ID NO: 4, 5 and 6.
3 . The antagonistic antibody of claim 1 , wherein said antibody binds specifically to the extracellular domain of CD16A and CD16B on monocytes, macrophages, NK cells and neutrophils, without inducing intracellular signal events in said cells.
4 . The antibody or fragment of claim 1 , wherein the dissociation constant (KD) of said antibody or fragment with CD16AV158 is comprised between 5 nM and 20 nM measured by Surface Plasmon Resonance.
5 . The antibody or fragment of claim 1 , wherein it is a chimeric or humanized antibody that has been recombinantly modified by introducing a N297A mutation in the human IgG1 heavy chain.
6 . A pharmaceutical composition comprising the antibody or fragment according to claim 1 , and a pharmaceutically-acceptable carrier.
7 . A kit comprising the antibody or fragment according to claim 1 and means for detecting said antibody or fragment when bound to CD16A or CD16B.
8 . The kit of claim 7 , wherein said antibody or fragment is conjugated to a labelling molecule, and said means comprise film sensitive to the radio- or chemi-luminescent label, or wherein said antibody or fragment is conjugated to a labelling tag molecule such as histidine or c-myc tag, and said means comprise an antibody which recognizes said tag molecule.
9 . The antibody or fragment according to claim 1 , wherein it is conjugated to a toxin molecule such as a ribosyl transferase, serine protease, guanyl cyclase activator, calmodulin-dependent adenyl cyclase, ribonuclease, DNA alkylating agent or mitosis inhibitor.
10 . The antibody or fragment of claim 2 , wherein it is a chimeric or humanized antibody that has been recombinantly modified by introducing a N297A mutation in the human IgG1 heavy chain.
11 . A kit comprising the antibody or fragment according to claim 2 and means for detecting said antibody or fragment when bound to CD16A or CD16B.
12 . The kit of claim 11 , wherein said antibody or fragment is conjugated to a labelling molecule, and said means comprise film sensitive to the radio- or chemi-luminescent label, or wherein said antibody or fragment is conjugated to a labelling tag molecule such as histidine or c-myc tag, and said means comprise an antibody which recognizes said tag molecule.
13 . The antibody or fragment according to claim 2 , wherein it is conjugated to a toxin molecule such as a ribosyl transferase, serine protease, guanyl cyclase activator, calmodulin-dependent adenyl cyclase, ribonuclease, DNA alkylating agent or mitosis inhibitor.