Rabbit corneal allograft survival following topical administration of cyclosporin A.

Cyclosporin A (CS-A), selectively inhibited cellular immunity, delayed the skin graft-induced rejection of corneal allografts in rabbits when administered subconjunctivally in the dose of 3 mg/kg/day or in the form of 5% water-soluble drops five times daily for 28 days. The subconjunctival application of CS-A was irritating, whereas the topical instillation of the water-soluble preparation was well tolerated. The corneal grafts were rejected after discontinuation of the therapy. Rejection was confirmed by scanning and transmission electron microscopy. The mechanism by which CS-A delayed corneal graft rejection seems to depend mainly on the specific and/or the nonspecific effect of topical CS-A on lymphocytes.