[Determination of antiplatelet antibodies on the surface of platelets by direct radioimmune method in patients with different types of immune thrombocytopenia].

Direct radioimmune assay (RIA) have been developed for detection of antibodies associated wild platelet membrane. Platelets from 12 patients with idiopathic thrombocytopenic purpura (ITP) and 27 patients with chronic lymphocytic leukemia (CLL) (platelet count (100,000 in 1 microliters) have been tested. Antibodies on platelets surface have been detected in all 12 patients with ITP and in 21 patients with CLL. In 6 CLL patients the number of immunoglobulins associated with platelets surface does not increase control level. It is possible, that in some CLL patients development of thrombocytopenia is mediated not only by platelet associated antibodies but by other mechanisms, one of which can be linked with the depression of megakaryocytes growth in bone marrow. Direct RIA for measurement of antibodies on platelet surface detect antiplatelet antibodies with higher frequency than indirect enzyme-linked-immunosorbent-assay (ELISA), developed earlier for assessment of antiplatelet antibodies in serum. Increase of platelet count in CLL patients after steroid and cytostatic treatment correlated with the decrease of platelet surface associated antibodies.