Synergism of RAD and cyclosporin A in prevention of acute rat corneal allograft rejection.

PURPOSE: The novel immunosuppressant RAD, 40-0-(2-hydroxy-ethyl)-rapamycin, has synergistic effects with cyclosporin A. The aim of this study was to evaluate the combined effect of RAD and cyclosporin A in the prevention of acute allograft rejection after murine corneal transplantation. METHODS: Fisher donor corneas were implanted into Lewis recipients. Postoperative evaluation included slit-lamp biomicroscopy and immunohistology. Treatment groups were comprised of rats treated orally with RAD 2.5 mg/kg/day, cyclosporin A 10 mg/kg/day, RAD 1.5 mg/kg/day plus cyclosporin A 5 mg/kg/day. RESULTS: Therapy with RAD 2.5 mg/kg and cyclosporin A 10 mg/kg led to a statistically significant and comparable prolongation of transplant survival. However. combination therapy was significantly superior. There was a significant reduction in the number of infiltrating cells in the animals treated with RAD and cyclosporin A. CONCLUSIONS: This is the first study on the efficacy of a double drug regimen with RAD and cyclosporin A for the control of acute corneal allograft rejection. Combination therapy resulted in superior graft survival.