Transfusion immunomodulation from a clinical perspective: an update.

Accumulated evidence demonstrates that allogeneic blood transfusions have clinically significant effects on the recipient's immune system. This transfusion immunomodulation effect is associated with an increased rate of cancer recurrence (uncertain causality) and post-operative infection (established causality). The exact mechanisms of transfusion immunomodulation are still unknown. Data suggests that transfusion immunomodulation is a biologic effect strongly associated with the infusion of allogeneic leukocytes. Soluble mediators that accumulate in transfused red cells and platelets during storage are also possible causes of post-transfusion complications. Some approaches can mitigate these effects. Most important is adopting more conservative transfusion practices. Leukoreduction (proven) and plasma depletion (proposed) are other methods to significantly reduce transfusion immunomodulation and its clinical sequela.