Effect of mycophenolate mofetil, cyclosporin A, and both in combination in a murine corneal graft rejection model

AIMS To compare the effectiveness of mycophenolate mofetil (MMF), cyclosporin A (CSA), and both in combination, in preventing rejection following corneal transplantations. METHODS Rats of the inbred strains Brown Norway and Lewis were used as donors and recipients respectively. MMF was administered orally in both monotherapy and combination therapy for 14 days in a dosage of 40 mg/kg body weight, and CSA was administered, likewise for 14 days, in an intramuscular dosage of 10 mg/kg body weight. The transplants were examined every third day by slit lamp microscopy. Every transplant was subjected to histological or immunohistological evaluation. RESULTS The average transplant survival rate in the allogenic strain combination was 7.9 days (SEM 1.1). Monotherapy with MMF led to a statistically significant prolongation of transplant survival to 11.6 days (SEM 0.9, p< 0.05). Monotherapy with CSA delayed transplant rejection statistically significantly longer than MMF (21 days, 0.0, p< 0.05). The combination therapy with CSA and MMF was statistically significantly superior to the monotherapy with MMF (22.3 days, 0.5, p< 0.05). The combination therapy prolonged transplant survival compared with the CSA monotherapy, albeit not to a statistically significant extent. CONCLUSIONS In this study we were able to prove the immunosuppressive effect of oral MMF on acute rejection following corneal transplantation. Double drug therapy with CSA and MMF conferred a marginal benefit without a higher incidence of complications related to drug toxicity or overimmunosuppression.