Immunologic effects of blood transfusion upon renal transplantation, tumor operations, and bacterial infections.

Blood transfusions appear to exert a suppressive effect on many aspects of the immune system. In transplantation, this has been used to advantage; in other areas, the consequences can be deleterious. It is likely that various components of the immune system are affected by different mechanisms and possibly by different components of transfused blood. Before rational strategies can be evolved for minimizing the deleterious effects of blood transfusions, it is essential that these mechanisms be clearly defined. Studies must take into account any influence the underlying disease state might have on the immune system. In the absence of any satisfactory substitute, blood transfusion remains an essential therapeutic modality in the management of surgical patients. With current evidence, however, it seems reasonable to avoid the administration of small-volume transfusions whenever possible and encourage the use of autodonated blood for elective surgery.