Effect of blood transfusions from different H-2 donors on immune responses in mice.

We studied the effect of blood transfusions (BT) from different H-2 donors on the induction of suppressor cells (SC) and of MLC inhibitory activity in serum in a drug-unmodified mouse model. Balb/c (H-2d) mice were transfused at weekly intervals with whole blood from donors of three strains using two transfusion protocols. In protocol I, blood was transfused first from C3H/HeJ (C3H) (H-2k), then C57Bl (H-2b), and then SJL (H-2s) strain mice, and in protocol II the order of blood donors was reversed. Spleen cells and serum samples were obtained from the transfused mice one and two weeks after the last BT. In both transfusion protocols, the kinetics of responses of cells from recipient transfused mice to cells from the blood donors in MLC were similar to those of cells from nontransfused mice. The peak responses of cells from transfused mice were consistently lower than those of cells from nontransfused mice. In cell-mixing experiments, radiosensitive SC capable of inhibiting responses of Balb/c mice to cells from all three blood donors in MLC could be demonstrated one week after the last transfusion in both protocols. Two weeks after the last BT, SC were demonstrable only against the first (C3H) blood donor in protocol I, and against all three blood donors in protocol II. Serum obtained one week after transfusion in protocol I inhibited responses of Balb/c mice to stimulator lymphocytes from all three blood donors in MLC. Serum obtained two weeks after BT, however, inhibited responses of recipient mice only to the first blood donor. In contrast, in protocol II, serum obtained both one and two weeks after BT did not cause inhibition of responses of cells from Balb/c mice to blood donor cells in MLC. Similar results were obtained when Balb/c mice were transfused at weekly intervals with whole blood from either C3H or from SJL mice. The data suggest that the induction of SC and/or MLC-inhibitory activity in the serum after BT is dependent on the H-2 type of the first blood donor.