Platelet crossmatch testing for donor selection.

Recent studies have shown that on an average the platelets of 20-30% of HLA fully compatible donors provide poor post-transfusion platelet responses in alloimmunized refractory thrombocytopenic patients. Conversely, some HLA incompatible transfusions can provide satisfactory platelet increments for the refractory recipient. To improve the process of selecting compatible platelet donors, both lymphocytotoxic and platelet crossmatch tests have been used. Lymphocytotoxicity crossmatch tests can predict the transfusion response only 65% of the time with a high percentage of false-negative results. In contrast, several different laboratories are now reporting 84-93% predictability for platelet crossmatch tests. Because of the time and effort involved in obtaining platelets from apheresis donors and the risk of bleeding in patients not provided with compatible platelets, it seems inevitable that platelet crossmatch tests will assume an increasingly important role in the donor selection process.