Platelet Antigen Recognized by Anti-Platelet Antibody in Two Cases of Chronic Idiopathic Thrombocytopenic Purpura

Abstract

Anti-platelet antibody in the sera from thirty-one patients with thrombocytopenia, and the platelet antigen which the antibody recognized, were studied by the method of immunoblotting. Anti-platelet antibody were detected in two patients with chronic idiopathic thrombocytopenic purpura (ITP), out of four acute ITP, twenty-two chronic ITP, three aplastic anemia, two acute lymphocytic leukemia that were refractory to platelet transfusion. Platelet antigen that the antibody recognized was apparently different from HLA-ABC antigen, and their molecular weights were 90kD, 55kD, 48kD in one case, 50kD, 38kD, 37kD in the other case. The diversity of the platelet antigen detected in this study indicates the complexity of the pathogenesis of chronic ITP.
Two antigens, of which molecular weight were 50kD and 38kD, were detected in the mononuclear cell fraction of normal peripheral blood. It is not clear whether these antigens were expressed constitutively on the mononuclear cell, or platelet antigen were adsorbed on the surface of mononuclear cell.