Modification of allograft survival in rats by blood transfusion to the donor.

In the BN/Ro-to-WAG/Ro rat donor-host combination, third-party blood transfusions given to the donor shortly before transplantation can markedly influence heart allograft survival if the immune response of the recipient has been modulated. The WAG recipients were either transfused with BN donor blood, which leads to a permanent graft survival, or postoperatively treated with a single i.m. injection of 15 mg/kg cyclosporine, which leads to a moderate prolongation of graft survival. In the transfused recipients, blood transfusions to the donor had a detrimental influence on graft survival. In the cyclosporine-treated recipients, blood transfusions to the donor had a beneficial effect. There was no significant difference in graft survival after a single transfusion or multiple transfusions to the donor. Recipient-type blood transfusion to the donor did not influence graft survival, nor did irradiated third-party blood or third-party erythrocytes. However, third-party leukocyte suspensions had a significant influence on heart allograft survival. It is concluded that third-party viable leukocytes are responsible for the induction of the donor transfusion phenomenon. It is also postulated that the third-party leukocytes interact with the dendritic cell population of the graft, leading to a reduction in its immunogenicity.