The role of platelet-activating factor in cell infiltration in endotoxin-induced uveitis in guinea pigs

Purpose. We investigated the role of platelet-activating factor (PAF) in cell infiltration in endotoxin-induced uveitis (EIU) in guinea pigs. Methods. To elicit EIU, lipopolysaccharide (LPS) was injected into the anterior chamber of the eye. Cell numbers in the aqueous humor after LPS injection were determined by flow cytometry. PAF and prostaglandin E-2 (PGE(2)) production after LPS injection were also examined. Results. Intracameral injection of LPS induced cell infiltration into the anterior chamber, and platelet-activating factor (PAF) was detected in the aqueous humor. In addition, topical apafant (PAF antagonist) partially inhibited cell infiltration. Intracameral injection of PAF scarcely induced cell infiltration but the reaction with EIU was accelerated by intracameral injection of a small amount of PAF. Conclusions. These results suggest that PAF has weak direct activity on cell infiltration in intraocular inflammation but enhances intraocular inflammation.