Abstract: 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 Fc?RIIIA (CD16A) and Fc?RIIIB (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).

Abstract: The present invention relates to the prevention and/or treatment of arthritic, inflammatory and/or allergic reactions as well as thrombocytopenia, by blocking the human receptors FcyRI and FcyRIIA. It is disclosed a mouse monoclonal antibody (mAb) which efficiently blocks human FcyRI and can therefore be used, alone or in a combination product, for example with an anti-hFcyRIIA blocking antibody, in the prevention and/or the treatment of these diseases.