Blood transfusion and organ transplantation.

Blood transfusions given to patients before renal transplantation are associated with improved subsequent graft survival. Non-specific lymphocyte inhibitory activity of plasma is demonstrated in those patients who have received blood transfusions. The activity is directed against the patient's own lymphocytes and is mainly associated with the alpha-2 macroglobulin fraction of plasma. In an animal model blood transfusions are associated with improved graft survival, and the timing of the transfusions before transplantation is important. The administration of alpha-2 macroglobulin is also important in prolonging graft survival. The therapeutic implications of these findings in clinical transplantation are discussed.