The problem of platelet autoantibodies. II. The applicability of the 14C-serotonin release test.

To evaluate the applicability of the 14C-serotonin release test for the demonstration of platelet autoantibodies, normal test material (sera, plasmas, globulin fractions), HLA-specific complement-fixing platelet antibodies and aggregated human gamma-globulin (agammaG) were tested in comparison to sera (plasmas, globulin fractions) of 101 thrombocytopenic patients including 46 cases of idiopathic thrombocytopenic purpura. Whereas defined immunological stimuli (HLA antibodies, agammaG) were detected with satisfactory precision, platelet autoantibodies could not be demonstrated. Only sera containing HLA antibodies due to previous immunization induced reproducible 14C-serotonin release. Results with test material from thrombocytopenic patients were analyzed by 2 x 2 tables and inconsistencies were shown to be caused by methodological variations.