PERIODIC PRODUCTION OF ANTIPLATELET AUTOANTIBODY DIRECTED AGAINST GPIIIA IN CYCLIC THROMBOCYTOPENIA

We report here a female patient with cyclic thrombocytopenia associate d with antiplatelet autoantibodies. There was an inverse relationship between the level of platelet-associated IgG and platelet count. Bone marrow megakaryocytes were normal in number even during the thrombocyt openia. The binding of monoclonal antibodies (mAbs) against glycoprote in (GP) IIb/IIIa to patient platelets was significantly inhibited in t he thrombocytopenic phase, while these mAbs normally bound to patient platelets obtained during the normal platelet count. Western blotting and mAb-specific immobilization of platelet antigens showed that both plasma autoantibody and the eluted IgG from the patient platelets boun d to GPIIIa. These results suggest that the periodic production of ant iplatelet autoantibody against GPIIIa caused cyclic destruction of pla telets in this patient.