Limb allotransplantation in the rat: extended survival and return of nerve function with continuous cyclosporin/prednisone immunosuppression.

We report the variability of the rejection process among the several tissues of a limb allograft. We used a rat hind limb allograft model transplanting across a well-defined minor histocompatibility barrier (Fischer RT-1(1v1)), donor animals, and Lewis (RT-1(1)) recipient animals. Continuous cyclosporin and prednisone immunosuppression was used. Four immunosuppressive regimens all produced extended limb survival. The rejection process was most severe and difficult to control in the skin. Nonskin tissues reverted to a nearly normal appearance after a period of cellular infiltration 2 to 3 weeks posttransplantation. Clinical and electromyographic evidence of nerve regeneration and end-organ reinnervation was demonstrated in long-term surviving animals.