The Effect of Donor Strain Blood Pretreatment on Renal Allograft Rejection in Rats

SUMMARY In the experiments reported here, the effects of both single and multiple i.v. injections of donor strain blood have been investigated in both DA and Lewis recipients of (DA X Lewis) F1 renal allografts. The (DA X Lewis) F1 to Lewis model represented the stronger incompatibility and was characterised by vigorous unmodified rejection, ready production of lymphocytotoxins, and difficulty in induction of specific immunosuppression. In the (DA X Lewis)F1 to DA model, unmodified rejection was sometimes spontaneously reversible, lymphocytotoxin production was weak or absent, and specific immunosuppression was easily induced. In both strain combinations, the timing of single exposures to donor strain blood was critical. Exposures 1 day pregraft resulted in sensitisation in the F1 to Lewis model and no effect in the F1 to DA model. If the grafts were delayed until 7 days after exposure to blood, then immunosuppression was the result in both models, but was far more effective in F1 to DA transplants, where most recipients went on to be long-term survivors. By 4 weeks after exposure to blood, immunosuppression was still present in the F1 to DA model but had virtually disappeared in the F1 to Lewis model. Multiple exposures to blood were more effective than single exposures for the production of immunosuppression. In many experimental groups, donor-specific lymphocytotoxins induced by the blood transfusions were present at the time of grafting, but in no case was hyperacute rejection seen.