Studies from our laboratory have demonstrated the release of high levels of neutrophil
chemotactic factors (NCF) from isolated rabbit corneas injured by
hydrogen peroxide (H2O2). The purpose of the present study was to determine the
biological activity of these factors and to test the hypothesis that the
intracameral injection of these factors can induce
inflammation of the anterior segment. Under sterile conditions, the epithelial surfaces of isolated rabbit corneas were incubated with
a 300 ul mixture of
glucose (G) (1mg/ml) and
glucose oxidase (GO) (20 U/ml) at 37 degrees C for 6 hours. This supernatant
solution was collected and a 100 ul sample containing NCF, but not H2O2, was injected into the anterior chamber of anesthetized rabbit eyes (n = 8). Anterior chamber
inflammation, characterized by moderate
corneal edema associated with a fibrinous anterior chamber reaction, was evident 2 and 4 hours after injection. Aqueous humor analysis revealed the presence of
fibrin and a large number of neutrophils (32 +/- 5 x 10(4) cells/ml). Control eyes, on the other hand, showed normal morphology and low levels of neutrophils after the injection of 100 ul minimum essential medium (MEM) (n = 8) (1.2 +/- 0.14 x 10(4) cells/ml), G/GO mixture (n = 8) (5 +/- 0.86 x 10(4) cells/ml), or supernatant solutions collected from MEM-treated corneas (n = 8) (15 +/- 2 x 10(4) cells/ml). To determine whether the inflammatory reaction observed was due to a direct effect of the
chemoattractants or mediated through stimulation of
arachidonic acid (AA) metabolites, we pretreated rabbit eyes with a sterile
solution of 0.1%
dexamethasone (n = 8 eyes) or with a sterile
solution of 3.4%
indomethacin (n = 8 eyes) three times a day, for one day, prior to the injection of NCF supernatant
solution. Examination 2 hours and 4 hours after injection revealed
inflammation characterized by mild-to-moderate
corneal edema associated with a fibrinous anterior chamber reaction was observed with or without prior treatment with AA metabolite inhibitors. No difference in the degree of
inflammation was detected clinically. Results of these studies suggest that NCF released from H2O2-injured corneas can directly induce
inflammation of the anterior segment, and that metabolites of AA are not mediating the observed in vivo response.