Induction of zymosan‐air‐pouch inflammation in rats and its characterization with reference to the effects of anticomplementary and anti‐inflammatory agents

Abstract

1 Induction of an experimental inflammation of the air-pouch type with the aid of zymosan (known to activate the alternative pathway of the complement system) was carried out in an attempt to induce a reproducible inflammatory model suitable for quantitative studies. 2 Rats were injected subcutaneously with 8 ml of air on the dorsal surface to make an air-pouch, followed 24 h later by 4 ml of 1.6% (w/v) zymosan suspension. This induced inflammatory responses. 3 Treatment with zymosan suspension provoked exudation of fluid, accumulation of polymorphnuclear leukocytes (PMN) in the pouch and the development of granulation tissue as a wall of the pouch. Approximately half of the PMN in the pouch formed a characteristic layer of aggregated cells sticking onto the inner surface of the pouch wall. They were counted after being completely disaggregated by means of incubation with trypsin. 4 In preliminary experiments with potential anti-inflammatory drugs, local application of a novel anti-complementary agent, K-76COONa, inhibited leukocyte accumulation in the pouch, whereas the potent anti-inflammatory agent, dexamethasone, was ineffective. By contrast, exudation of the pouch fluid was effectively inhibited by dexamethasone but not by K-76COONa.