Antibody studies in a patient with acute thrombocytopenia following infusion of plasma containing anti-PI(A1).

Immune thrombocytopenia due to passive transfer of anti-PI(A1) alloantibody has been noted as a rare but potentially dangerous complication of plasma transfusions. We report a patient with a preoperative platelet count of 241 x 10(9)/l who developed severe thrombocytopenia within 2 hr following transfusion of 2 U of fresh frozen plasma. The plasma donor was found to be a PI(A1)-negative woman. The platelet count of the PI(A1)-positive patient recovered within 7 days to normal values. In the frozen plasma, excessive antibody binding to GPIIb-IIIa on the recipient's platelets was detected. The antibody was shown to have anti-PI(A1)-specificity. Only 40 min after transfusion of the frozen plasma, no antibody was detected in the plasma of the recipient. This case suggests that passively administered anti-PI(A1) alloantibody is immediately adsorbed onto the recipient's platelets and thus removed from circulation.