[Suppression of the mixed lymphocytic reaction by autologous red cells and their constituents: a new hypothesis on the apparent tolerogeneic effect of blood transfusions during transplantation].

Using the lymphocyte reaction (MLR) as an in vitro model of allogeneic response we have demonstrated that red blood cells (RBC), when phagocytosed by monocytes present in the reaction, induce almost complete suppression of the MLR. A similar effect is achieved by the RBC lysate or purified hemoglobin. These data strongly suggest that the better graft tolerance apparently induced by blood transfusion given to the recipient at the time of transplantation may result from a non specific immunodepressive process induced by the injected erythrocytes, and mediated by the monocyte.