Post-transfusion purpura responding to high dose intravenous IgG: further observations on pathogenesis.

A typical case of post-transfusion purpura (PTP) is described in a 61-year-old woman. Treatment with steroids corrected the purpuric manifestations, but the patient remained thrombocytopenic in spite of steroid therapy and plasma exchange. However, an intravenous infusion of high dose IgG led to a rapid and sustained increase in the platelet count. The mechanism of thrombocytopenia in PTP is still a matter for speculation, as the platelet specific antibody usually cannot be shown to react with the patient's own platelets in vitro. Therefore, the finding of a coexistent platelet specific IgM autoantibody in this patient, first detected during the early recovery phase, is of particular interest and suggests a possible autoimmune basis for the profound thrombocytopenia.