[Clinical and serologic studies in 34 patients with post-transfusion purpura]

Posttransfusion purpura (PTP) is a rare transfusion reaction characterized by a severe bleeding tendency and thrombocytopenia which occurs approximately 1 week after transfusion of platelet-containing blood components in patients previously immunized against platelet alloantigens. 34 cases of PTP were studied. Our patients were all female with a mean age of 60.8 years (35-78 years, n = 32). The inciting blood components were whole blood (4) or red cell concentrates (28). The interval between transfusion and onset of purpura ranged from 2 to 14 days with a clear maximum at 7 and 8 days. In 11 of 13 patients (85%) transfusion was accompanied by febrile, nonhemolytic transfusion reactions. Hemorrhagic symptoms lasted 9.4 days (3-37 days, n = 16). The mean minimal platelet count was 7.1 x 10(3)/microliters [(0-28) x 10(3)/microliters, n = 29]. The platelet count rose to over 50 x 10(3)/microliters after 13.9 days (2-61 days, n = 26), over 100 x 10(3)/microliters after 17.0 days (3-75 days, n = 22). In 1 patient, PTP led to death due to intracranial hemorrhage. 22 patients were treated with corticosteroids, 20 patients with intravenous immunoglobulins (IVIG), 17 of these patients received both. Therapy with IVIG was successful in 14 of 19 patients, whereas platelet transfusions (n = 18) were not able to evaluate the platelet count. Serological analysis showed that antibodies against the HPA-1a antigen either alone (18), in combination with HLA antibodies (12) or with anti-HPA-5b (1) were responsible in 91.2%, while antibodies against other platelet antigens were rarely implicated. In elution experiments HPA-1a antibodies could be eluted from the autologous HPA-1a-negative platelets. We suppose that these antibodies had a pseudo-specificity and were involved in the destruction of the patients' own platelets.