Kidney and spleen twin grafts in rats: unidirectional graft acceptance in unsuppressed ACI recipients

In previous studies, we have shown that vascularized spleen grafts can facilitate the acceptance of simultaneously implanted hearts, especially if host splenectomy is done 3 days later. The present study shows that the same protocol works not only for hearts but also for kidneys. A total of 59 renal allografts were carried out in various combinations between LEW and ACI rats. The recipients were submitted to bilateral nephrectomy at the time of graft implantation and host splenectomy 3 days later. Graft function was assessed by survival time of the animals. In addition, BUN, creatinine, and hematocrit were measured in selected individuals. The following observations were made: 1) LEW kidneys were rejected at 92 +/- 65 days while ACI kidneys failed at 17 +/- 1.4 days (p less than 0.025). 2) Control animals without simultaneous syngenic functioning spleen implant rejected their LEW kidneys at 30.6 +/- 24.3 days (p less than 0.005). 3) Eleven rats never rejected their LEW kidneys (four single, seven twin grafts). 4) BUN, creatinine, and hematocrit differed significantly in rats with functioning kidneys compared to those in end stage renal failure (p less than 0.0005, p less than 0.0025, and p less than 10(-7) respectively). It is concluded that the presence of the donor spleen can facilitate the acceptance of a simultaneous kidney graft to various degrees, depending on the strain combination.