[The syndrome of post-transfusion purpura].

Thrombocytopenic purpura occurred in two women aged 67 and 77 years, who earlier on had been pregnant, six and twelve days after blood transfusions. The platelet deficient phase lasted 16 and more than 50 days. Differentiation from other causes of thrombocytopenic haemorrhage was based on immunohaematologic findings. Both patients were negative for the platelet specific antigen PlA1 (Zwa). The platelet specific antibody (anti-PlA1) responsible for the purpura could be demonstrated and characterised immunologically.