Use of in vitro assays in selection of compatible platelet donors.

Although HLA-matched platelet transfusions are of value in the support of some alloimmunized thrombocytopenic patients, poor posttransfusion increments can be observed following HLA-matched platelet transfusions and conversely good posttransfusion increments may result after HLA-mismatched platelet transfusions. We have explored the possibility that in vitro assays in addition to HLA typing might better select compatible donors for refractory recipients. Our studies suggested that a platelet migration inhibition assay is predictive of platelet transfusion responses in HLA-compatible and incompatible donor-recipient pairs, while lymphocytotoxicity is predictive of posttransfusion increments only in HLA-incompatible donor-recipient pairs. Granulocytotoxicity, microleukoagglutination, and capillary leukoagglutination showed no value in predicting platelet transfusion increments, either in HLA-compatible or incompatible donor-recipient pairs.