[Risk of immunization to blood cells and diagnostic and therapeutic implications].

Transfusion of blood and blood components may be fraught with serious immunologically mediated side effects. Acute hemolytic reactions are still the most common cause of fatal transfusion sequelae. The incidence of alloimmunization against erythrocyte antigens as studied in long-term transfused patients with thalassemia depends on the age at the beginning of transfusion therapy. HLA alloimmunization is often associated with refractoriness to platelet transfusions and febrile transfusion reactions. Neonatal alloimmune thrombocytopenia and post-transfusion purpura are elicited by platelet-specific antibodies reacting with determinants on platelet glycoproteins IIb/IIIa, Ib/IX, and Ia/IIa. Another serious complication of transfusion therapy, transfusion-related acute lung injury, is caused by granulocyte-specific alloantigens in donor plasma. Graft-versus-host disease is a rare but dangerous complication of blood transfusion which mainly affects patients with impaired T-cell-related immunity.