Post-Transfusion Purpura: Immunologic Aspects and Therapy

Abstract To determine the mechanisms of post-transfusion thrombocytopenia, platelet antibodies were studied in a 45-year-old woman in whom severe thrombocytopenia with lingual and buccal hemorrhagic bullae and purpura developed seven days after the transfusion of whole blood. Her platelets were later typed as PlA1 negative, and her plasma and serum contained anti-PlA1 and anti-HLA antibodies. Antibody activity was demonstrated by microscopical agglutination and lysis, by aggregation with use of an aggregometer, and by 51Cr release. Antibody activity, as measured with the aggregometer, seemed restricted to the IgG3 class of immunoglobulin. Plasmapheresis resulted in clinical improvement associated with disappearance of antibody activity. Thus, this patient with post-transfusion purpura demonstrated anti-PlA1, and anti-HLA (IgG3) anti-platelet antibodies. Plasmapheresis with removal of the antibody proved effective therapy. (N Engl J Med 291:1163–1166, 1974)