Posttransfusion thrombocytopenia associated with passive transfusion of a platelet-specific antibody.

A transfusion reaction in a 76-year-old man was followed by severe but transient thrombocytopenia after infusion of whole blood. A high-titer platelet-specific antibody (anti-PLA) was demonstrated in the plasma of the implicated unit and in the serum of the blood donor. In addition, three previous recipients of blood from the implicated donor had posttransfusion episodes of unexplained thrombocytopenia. These cases represent the first reported clinical examples of posttransfusion thrombocytopenia caused by passively transfused platelet-specific alloantibodies.