Effects of interferon preparations on rabbit corneal xenograft

High doses of rabbit interferon (2 X 10(6) and 2 X 10(5) units/ml, a drop of about 0.1 ml administered topically into the eye twice daily) suppressed the rejection of rabbit corneal xenograft, whereas a low dose (2 X 10(3) units/ml) enhanced it, However, neither heat-inactivated rabbit interferon nor mouse L cell interferon showed any effects on rabbit corneal grafts.