The effect of systemic decomplementation with cobra venom factor on corneal complement levels in guinea pigs.

The authors examined the effect of systemic administration of cobra venom factor (CVF) on hemolytic complement levels in guinea pig sera and corneas. Guinea pigs received repeated intraperitoneal injections of CVF. Sera and corneas were obtained before and 1, 2, 5, 8, 10, 12, 16, and 20 d after the initial injection of CVF. Total hemolytic complement activity was measured by lysis of sheep erythrocytes sensitized with rabbit antibodies. There was a significant decrease in serum complement levels at days 1, 2, 5, 8, and 10 after the initial injection of CVF. After this, complement levels rose to levels that exceeded preinjection values. Complement levels in corneas also declined after CVF injections with a significant decrease at days 2, 5, 8, and 10 and a return to normal thereafter. Corneal complement depletion and restoration lagged behind serum. Moreover, the rate of complement depletion and restoration was greater for serum than cornea. Light microscopic examination of representative corneas at each time did not show local tissue changes during decomplementation. This is first study (to the authors' knowledge) to document corneal complement depletion by systemic administration of CVF. Low-to-absent corneal complement levels were present 2 d after the initial injection of CVF and persisted for 6 d. This model could be used to study the influence of complement on traumatic and immunologic injuries to the cornea.