Correction of poor platelet transfusion responses with leukocyte-poor HL-A-matched platelet concentrates.

Matching donor-recipient pairs for HL-A antigens provides a logical starting point for selecting donors for recipients with extensive prior transfusion histories. However, during the course of continued exposure to even HL-A-matched platelet concentrates, further sensitization occurs, as indicated by progressively poorer post-transfusion increments and transfusion reactions. There is evidence that such sensitization may be due to non-HL-A antigens. Finally, it is postulated that the poor post-transfusion platelet increments obtained when standard platelet concentrates are used result from the leukoagglutinin antigen-antibody reaction involving the platelet as an "innocent bystander." The standard platelet concentrate can be purified by a simple method of centrifugation (178 g times 3 min), removing about 96% of the contaminating white blood cells with concomitant loss of about 21% of the platelets. The use of these leukocyte-poor platelet concentrates can restore compatible transfusion increments in highly alloimmunized thrombocytopenic recipients. The luekocyte-poor concentrates can diminish undesirable transfusion reactions following imcompatible platelet transfusions.