1. Blood transfusion confers immune suppression with improved allograft survival. The aim of this study was to evaluate the effect of blood transfusion on the production of T-helper-2 cytokines and transforming growth factor β, which are associated with suppression of allograft rejection. An additional aim was to try to identify which blood cell type is mostly responsible for the blood transfusion effect. Production of interleukin-4, interleukin-10 and transforming growth factor β by peripheral blood mononuclear cells isolated from patients with end-stage renal disease was measured in vitro. These assays were performed before, and 4 h, 4, 7 and 14 days after a single blood transfusion and the transfusion of one unit of leucocyte-free erythrocytes.
2. Blood transfusion stimulated a significant rise in the production of all three cytokines measured. Transfusion of erythrocytes had no effect on the production of interleukin-4 or interleukin-10.
3. It is suggested that blood transfusion enhances the production of interleukin-4, interleukin-10 and transforming growth factor β. These cytokines may inhibit production of T-helper 1 and pro-inflammatory cytokines, deactivate cytotoxic cells and thereby suppress allograft rejection. It is further suggested that the leucocyte is the transfused cell type which is mostly associated with induction of this immunosuppressive response.