Post transfusion purpura(PTP), is a rare but serious transfusion associated complication characterized by purpura and thrombocytopenia, five to twelve days after a transfusion. It occurs due to human platelet antigen(HPA) alloimmunisation following sensitization from either blood product transfusion or during pregnancy. Blood components most frequently implicated in PTP are packed red blood cells, but it can also occur after platelet and plasma transfusions. The common antibodies detected in PTP are anti-HPA-1a, followed by HPA-1b, HPA-5b, and HPA-3a. The platelet antibodies destroy both transfused and autologous platelets. The low platelet count is generally unresponsive to transfusion of antigen-positive or antigen-negative platelets. If untreated, the disease is self limited with platelet recovery within 21 days. Recommended treatment is with IVIG.
Detection of anti-HPA-5b in a patient with post transfusion purpura