Post-transfusion purpura.

Post-transfusion purpura (PTP) is an acute episode of severe immune thrombocytopenia occurring about a week after transfusion. It is closely associated with alloimmunisation by platelet specific antigens, and usually affects a PlA1 negative woman who has been previously immunised by a PlA1 positive pregnancy. The transfusion precipitating PTP provokes a secondary (anamnestic) response which boosts the patient's anti-PlA1 antibody, but it remains uncertain how this relates to the destruction of the patients own PlA1 negative platelets. The accumulated information gained from the intensive study of an increasing number of cases of PTP from many centres has revealed a wider clinical and serological spectrum of PTP, and this has led to a better understanding of the pathogenesis and treatment of the condition. These aspects of PTP are the subject of this review.