Effect of blood transfusions on immune function. III. Alterations in macrophage arachidonic acid metabolism.

Blood transfusions have been shown to prevent allograft rejection, to increase the rate of tumor growth, and to increase susceptibility to infectious complications. We evaluated the mechanism of this immunosuppression by studying the effect of transfusions on macrophage function in a Lewis rat model. Allogeneic transfusions were found to decrease macrophage migration in response to inflammatory stimuli and to increase their production of the strongly immunosuppressive arachidonic acid metabolite prostaglandin E. Syngeneic transfusions did not alter macrophage migration or arachidonic acid metabolism. The immunosuppression seen following transfusions appears to be related to an increased synthesis of prostaglandin E.