Suppressor cell induction in donor-specific transfused mouse heart recipients.

Administration of donor-specific blood presenting major or minor foreign histocompatibility antigens to the mouse recipient improved heart allograft survival when a single transfusion of 0.25 ml was given to the recipient prior to transplantation. Multiple transfusions did not prolong allograft survival, which suggested a presensitization effect. In addition, when the single transfusion volume was reduced to 0.025 ml, no significant effect in prolongation of graft survival was observed. Thus the amount of blood transfused seemed to be a critical factor in achieving the transfusion effect. Splenic suppressor cells after transfusion and transplantation (as determined by adoptive transfer) were present during the stable maintenance phase of graft survival in transfused recipients with long-term surviving heart allografts. Also, an intact spleen was required to achieve improved allograft survival in mice transfused with donor-specific blood. Thus a mechanism for the favorable effect of blood transfusion may be the generation of splenic suppressor cells in response to transfusion followed by transplantation.