The problem of platelet autoantibodies. I. Evaluation of the platelet factor 3 availability test for their detection.

To assess two modifications of the platelet factor 3 (PF3) test for platelet antibody detection, an analysis of test conditions was performed with normal test material (serum, plasma, globulin fraction), defined HLA-specific, complement-fixing antisera and a quinidine-induced antiserum. It was shown that, under standardized conditions, the PF3 test revealed known platelet antibodies confirming earlier results. Its reproducibility and, to a lesser degree, its sensitivity were inferior to platelet complement fixation. In contrast, the test did not permit the reliable determination of platelet autoantibodies in sera of 89 thrombocytopenic patients including 36 cases of idiopathic thrombocytopenic purpura. Positive results loosely corresponded to the presence of HLA antibodies in sera.