[Post-transfusion purpura: clinical and immunologic studies in 38 patients]

Posttransfusion purpura (PTP) is characterized by severe thrombocytopenia and hemorrhagic diathesis about 1 week following blood transfusion. Only few studies exceed the description of single cases.

Clinical data from 38 patients were analyzed. Platelet antibodies were studied by complement binding, immunofluorescence, MAIPA assay and acid elution techniques.

All patients were female. The mean age at onset was 60.7 years (35-78 years). 4 patients received whole blood, 28 were transfused with packed RBC. 11 of 13 patients (85%) had febrile, non hemolytic adverse reactions during the transfusion. The interval between transfusion and onset of purpura extended from 2 to 14 days, with a peak at 7 and 8 days. Hemorrhagic symptoms lasted 10.1 days. The minimal platelet count was 7.0 x 10(3)/microliters. The platelet count increased to over 50 x 10(3)/microliters after 13.9 days (n = 26), and to over 100 x 10(3)/microliters after 17.0 days (n = 22). 2 patients died of hemorrhagic complications. 24 patients were treated with glucocorticoids, 20 with intravenous immunoglobulins (ivIG), 17 of these received both therapies. 14 of 19 patients (74%) responded well to ivIG. In contrast, platelet transfusions produced no adequate increment, in 6 cases they provoked febrile reactions. 35 sera (92.1%) contained anti-Zwa, either alone or together with anti-HLA or in 1 case with anti-Bra. Anti-Baka and anti-Bakb were found in 1 case each. In 5 patients, anti-Zwa could be eluted from autologous Zwa-negative platelets.

The broad clinical spectrum of PTP could be shown. Since 5% of the patients succumb to bleeding complications, the application of ivIG as therapy of choice is recommended. The phenomenon of elution of alloantibodies from autologous platelets is interpreted as a consequence of 'pseudo-specificity' which may play a role in the pathogenesis of PTP.