The mechanism of specific immunosuppression of renal allograft rejection by donor strain blood.

Abstract

SUMMARY The experiments reported here attempt to define suppression of rejection induced in DA and Lewis recepients of(DA × Lewis)F1 renal allografts by pretreatment with donor strain blood,Cytotoxicity inhibition assays suggested the presence of soluble histocompatibility antigens in DA serum but not in Lewis serum. However, pretreatment with DA serum had no effect on F1to lewis renal allografts. Thus, the immunosuppression induced by whole blood was attributable to histocompatibility antigens on the formed elements of the blood.Long surviving (DA × Lewis) F1 kidneys in Lewis recipients retransplanted to normal, untreated Lewis rats were rejected much more slowly than controls, showing that incomplete graft adaptation had occurred. Fresh (DA X Lewis) F1 kidneys were not rejected by long survivors, showing that the immunosuppressive effect induced at the time of transplantation had persisted indefinitely. Attempts to demonstrate enhancing factors in long survivors by both passive transfer of serum and adoptive transfer of spleen cells were ineffective. Long survivors rejected donor strain skin grafts with only a slight delay and had normal graft-versus-host (GVH) reactivity to donor strain antigens. These results favour enhancement as the mechanism of immunosuppression, but they neither implicate it firmly nor do they exclude the possibility of tolerance