T cell-derived factor alone or in combination with immunosuppressive drugs augments prolongation of allogeneic skin graft survival in mice receiving donor-specific transfusion.

Limiting dilution cytotoxicity or proliferation assays were performed with cells taken from A/J mice pretransfused with BALB/c blood. The data obtained indicate that donor-specific transfusion decreased both the frequency of reactive precursors and their proliferative potential after activation. Additional studies implied that these changes may be associated with a serum- or cell-mediated antigen-specific suppressive mechanism. Further manipulations aimed at preferentially sparing or enhancing the activity of suppressor T cells prolonged skin graft survival in pretransfused mice and led to the presence of suppressor T cells in the spleen of such mice, which were active upon adoptive transfer. These manipulations included the use of pretransplant donor-specific transfusion, administration of ALS or cyclosporin-A, or the use of posttransplant injection with a T suppressor activating factor (SAF). Optimum graft survival was associated with combined treatment when using transfusion, SAF, and cyclosporin-A.