PARTICIPATION OF MACROPHAGES IN CHLORAMPHENICOL-POTENTIATED CARRAGEENAN-INDUCED PERITONITIS IN RATS

1. We investigated the possible potentiating effect of chloramphenicol succinate (30 mg/kg, every 12 h for 4 days, ip) on the response of po lymorphonuclear neutrophils to carrageenin (150 mug, ip) or dextran (1 00 mug, ip) in the peritoneal cavity of male Wistar rats (180-230 g; N = 12 in each group). 2. Chloramphenicol potentiated the cell migratio n induced by carrageenin (35%) but not that induced by dextran. Previo us macrophage depletion in the peritoneal cavity by washing with steri le saline abolished the cell response, whereas a previous thioglycolla te-induced increase in macrophage numbers enhanced the potentiating ef fect (60%). 3. These results suggest that the potentiating effect on p olymorphonuclear neutrophil migration induced by chloramphenicol may b e related to chemotactic factors released by macrophages.