Effect of in vivo treatment by dexamethasone and indometacin on DNA synthesis in rat macrophages in culture stimulated by inflammatory exudate.

The acute inflammatory exudate obtained 4 hr after intrapleural injection of dextran in rats is able to induce DNA synthesis and division of normal rat macrophages in culture. The influence on this phenomenon of two types of pretreatment of rats with dexamethasone or indometacin has been investigated. Exudates of rats treated with dexamethasone decreased the DNA synthesis in control macrophages. On the contrary, exudates of rats treated with indometacin had no effect on this DNA synthesis. These results could be explained by the different actions of the two anti-inflammatory agents on cellular migration in pleural exudates. In macrophages harvested from rats treated with dexamethasone or indometacin the DNA synthesis induced by inflammatory exudates was decreased. This identical response elicited by these two agents could be related to their direct antimitotic activity on macrophages.