[HLA and transfusion]

Using published data, the role of the HLA system for transfusion of cellular blood components is described. Transfusion-associated immunomodulation and the causative role of HLA in other side effects of transfusion therapy are discussed, using review articles and original papers from the German and English literature as sources. The HLA system has important implications for transfusion therapy. Sensibilization of recipients with consecutive formation of HLA antibodies impairs the support of thrombocytopenic patients and may cause febrile transfusion reactions. HLA antibody formation in donors may result in transfusion-induced acute lung injury. The transfusion of viable lymphocytes may cause graft-versus-host disease in immunocompromised recipients or after directed donations from relatives, in rare cases even without these conditions. The clinical implications of transfusion-associated immunomodulation are judged differently.