Use of cyclosporin A in allotransplantation of rat limbs.

An experimental model for limb transplantation as a composite tissue transfer has been developed using two genetically well defined strains of rats, BUF and LEW. The study shows that cyclosporin A (CyA) is very effective as an immunosuppressive agent in preventing rejection of transplanted limbs in rats. It is found to suppress rejection of the homotransplants as long as treatment is continuous. No untoward side effects have been noted at the current experimental dosage of the medication. CyA is superior to the conventional agents, such as azathioprine and prednisolone, which allow rejection of the limbs while treatment is in progress. There is a period of immune tolerance following CyA treatment; however, this period becomes shorter as the length of the treatment is increased. This may indicate that CyA treatment should be continuous and not pulsed at the dosage used in this experimental model. Additional experiments are underway to further elucidate this phenomenon.