Effect of portal venous injection of donor spleen cells on skin allograft survival in rat.

BACKGROUND & OBJECTIVES Pretransplantation injection of donor lymphohaemopoetic cells via portal venous route has been shown to improve allograft survival in mice. In the present study, the effect of perioperative portal venous administration of donor splenocytes on skin graft survival was investigated in comparison with intravenous administration of spleen cells in Swiss albino rat skin transplant model. METHODS Using a single-donor survival study, skin allograft recipients received either no treatment, a single transfusion of donor spleen cells via portal vein or a single transfusion of donor splenocytes into vena cava. Spleen cell transfusion consisted 25x10(6) viable cells in a volume of 1ml given just before skin grafting. Skin graft survival was assessed by macroscopic appearance. Rejection was defined as the first day on which the entire surface of the graft was necrotic. Histologically necrosis, increased connective tissue, vascularity and polymorphonuclear leucocyte (PNL) infiltration were evaluated under light microscopy. RESULTS In this survival study of skin allografts, with the injection of viable spleen cells into portal vein concomitant to skin grafting, significant prolongation of mean allograft survival was induced (20.3 days), compared with untreated recipients (6.5 days, P<0.001). In the histopathologic evaluation, less PNL infiltration, necrosis, increased vascularity and connective tissue repair were observed in vena porta group with no statistical significance. INTERPRETATION & CONCLUSION It may be possible to develop protocols to induce transplantation tolerance based on the historical concept of donor specific antigen administration. However, it appears that donor spleen cell transfusion alone is not sufficient to prevent graft rejection. Thus, more efficient combination treatments are required to induce a state of durable tolerance.