Mechanisms and new approaches for the allogeneic blood transfusion-induced immunomodulatory effects

Abstract

ELLULAR BLOOD components such as red cells, platelets, and granulocytes are routinely used for clinical conditions associated with deficits of these respective cells in patients. Because different alloantigens are present on donor blood cells, elicitation of humoral and cellular immune responses to these foreign antigens is expected. These immune responses could lead to various types of transfusion reactions, such as hemolysis, fever, lung injury, refractoriness to random donor platelets, and so forth. ~ In addition to these well-recognized immunologic reactions, a number of unintended and subtle immunologic consequences associated with transfusions of allogeneic blood components have also been reported. The best-documented consequence is the prolonged survival of renal allografts in patients who had blood transfusions before transplantation. 2,3 This finding indicates that allogeneic blood transfusion could enhance the acceptance of allografts and has prompted extensive investigation on the possible immunologic mechanisms for this intriguing phenomenon. 4 This finding also prompted a close examination of other possible clinical consequences that might have resulted from potential nonspecific immunosuppressive effect of allogeneic blood transfusion. The reported clinical consequences include increased risk of postoperative infection, 5,6 increased growth and dissemination of tumor cells] activation of latent viral infection, 8-1~ amelioration of immune inflammatory diseases,11 and prevention of recurrent spontaneous abortions. ~2,13 However, the causal association between these immunologic effects and allogeneic blood transfusion remains controversial, and the mechanisms for these effects are poorly defined. 13-15 Recent advances in the