Generation of complement-derived anaphylatoxins in normal human donor corneas

Complement-derived anaphylatoxins (C3a, C4a, and C5a) are potent, stable mediators of acute inflammation. Because human corneas contain functional complement, the authors subjected normal human donor corneas to various forms of immunologic or chemical injury to determine if the complement system could be activated and anaphylatoxins generated. The experimental cornea of each donor pair was injected with lipopolysaccharide (LPS) or immune complexes or injured by application of acid or alkali. The remaining cornea of each donor pair served as a control. After incubation of corneas in tissue culture media for 6 hours and elution in phosphate-buffered saline for 24 hours, C3a, C4a, and C5a were measured in corneal eluates by radioimmunoassay. Compared with control corneas, C3a levels were significantly increased in corneas injected with LPS or immune complexes and in corneas injured with acid or alkali. C4a levels were significantly elevated in corneas injected with immune complexes and in corneas injured with acid or alkali but not in corneas injected with LPS. C5a levels were detectable only in corneas injured with acid or alkali. These results suggest that immunologic reactions in the human cornea may activate the classic or alternative complement pathways and generate anaphylatoxins. Additionally, chemical injuries with acid or alkali generate anaphylatoxins in the cornea. Anaphylatoxins may participate in the acute inflammatory response of the human cornea to chemical or immunologic injury.