The effects of locally injected antibiotic on carrageenan-induced granuloma in rats

Indomethacin (0.5 mg/100 g b.w./day) and chloramphenicol (0.5 mg or 15 mg/100 g b.w./day) were tested for their anti-inflammatory effects on 7th day carrageenan-induced granuloma formation. Neither of the drugs modified granuloma or pouch wall weight but they decreased the exudate and the cluster of dead cells. Indomethacin and chloramphenicol decreased glucosamine in the dead cell granuloma fraction and increased the level of collagen in the pouch wall. The drugs differed in their inhibitory effect on lysozyme and prostaglandin E2 accumulation in the exudate. The increase in collagen was related to a drop in the level of prostaglandin E2 which seems to regulate collagen deposition in the granuloma. However, the prostaglandin E2-lysozyme correlation--which was only significant with chloramphenicol--suggests a mode of action for chloramphenicol different from that of indomethacin. Chloramphenicol could act by a myelodepressive and/or chemotactic effect. The effects of chloramphenicol on the macrophages are discussed.