PREDICTIVE VALUE OF CROSS-MATCHING FOR TRANSFUSION OF PLATELET CONCENTRATES TO ALLOIMMUNIZED RECIPIENTS

Compatibility tests in which donor platelets were tested with recipient sera were performed retroactively after 64 transfusions of platelets from 59 unrelated donors to 10 alloimmunized patients. Techniques used were serotonin release, aggregometry, platelet factor 3 release and lymphocytotoxicity, each of which was previously advocated as a means of testing donor-recipient platelet compatibility. Although false positive reactions were few (positive crossmatch but satisfactory transfusion response), false negative reactions (negative crossmatch but poor transfusion response) were unacceptably high (43% by lymphocytotoxicity, 60% by serotonin release, 76% by platelet factor 3 release and 83% by aggregometry). Current methods of detecting isosensitization to platelet alloantigens are less satisfactory than HL-A phenotyping in selecting unrelated platelet donors for an alloimmunized patient population.