The prolongation of skin allograft survival by topical use of cyclosporine A.

The absorption of CsA applied topically on normal or grafted skin was studied. When care was taken to prevent the rat from ingesting the CsA off their backs, the CsA blood levels was about 100 ng/mL or less, a suboptimal level to prevent rejection. The mean survival time of BUF grafts topically treated with 12 mg CsA/d was still significantly prolonged from 9.8 +/- 0.4 to 12.0 +/- 0.3 days. In bilateral grafting experiments where one graft was treated with CsA and one was not, the treated graft survived longer. Both grafts survived significantly longer than control animals with single grafts. These findings indicate that there is both a systemic and local immunosuppressive effect of topical CsA.