[Immunomodulatory effect of blood components transfusions]

In this paper the authors have described basic mechanisms of immunomodulation caused by blood transfusion and its clinical consequences. Transfusions of blood and blood components can induce cell interaction changing the immunological response of a recipient. Two phenomena--immunisation and immunosuppression result from post-transfusion immunological changes. The factors causing these two phenomena are not fully known. Immunomodulation observed as a consequence of blood transfusion is probably associated with a decrease of cell mediated-immunity and at the same time an increase of humoral immunity. The observed effects of transfusion include a shift of lymphocyte subpopulations from Th1 to Th2, a reduction of natural cytotoxic cell activity, CD4/CD8 ratio and blastogenesis of lymphocytes. Animal studies suggest that the mechanisms of immunomodulation are stimulated by leukocytes present in blood components. Animal data show that pre-storage leukoreduction is more effective than post-storage leukodepletion.