Effect of FK 506 administered topically versus intramuscularly on suppression of the corneal immune reaction in rats.

The immunosuppressive effect of FK 506 on penetrating keratoplasty in rats was evaluated following intramuscular and topical administration. Implanted corneal grafts were inspected weekly by clinical evaluation for 3 weeks. Cytotoxic T lymphocyte (CTL) activity was measured in the spleen on postoperative day 21, and the grafts were examined histologically. A dose of FK 506, 0.1 mg/kg given intramuscularly, only moderately suppressed CTL activity and the graft failed. In contrast, doses of either 0.024 mg/day topically or 0.3 mg/kg intramuscularly suppressed CTL activity and the grafts remained intact. Results suggest that FK 506 administered topically would be effective in preventing failure of human corneal grafts.