Effect of benzodiazepine on antigen-induced eosinophil infiltration into guinea pig conjunctiva

The effect of benzodiazepine (BZP) on experimental allergic conjunctivitis was studied. Male Hartley guinea pigs were sensitized with ovalbumin (OVA) and then homologous anti-OVA serum was injected intravenously into guinea pigs for passive sensitization. BZP was administered at a dose of 5 mg/kg by intraperitoneal injection (i.p.) according to the following schedule respectively; a single, repeated twice a day for 3 days, repeated twice a day for 3 days plus a single and repeated twice a day for 7 days. OVA challenge was performed to the conjunctiva, 20 minutes later, conjunctival edema during the early phase response (EPR) was observed and again at 6 hours later, both eosinophil infiltration into the conjunctiva and the platelet activating factor (PAF) serum level during the late phase response (LPR) were examined. BZP did not inhibit the development of conjunctival edema during the EPR. A single dose of BZP did not inhibit, but repeated doses of BZP for 3 or 7 days significantly suppressed eosinophil infiltration during the LPR. And after repeated doses of BZP for 7 days, all PAF serum levels during the LPR were under the lower detection limit of the assay. These results suggest that BZP has an inhibitory effect on antigen-induced eosinophil infiltration into the conjunctiva during the LPR.