Phagocytes, toxic oxygen metabolites and inflammatory bowel disease: implications for treatment.

Phagocytic cells are prominent in the inflammatory infiltrate of Crohn's disease and ulcerative colitis. These cells secrete a variety of agents which are thought to be important in the pathogenesis of tissue damage in inflammation. The function of phagocytic cells does not appear to be impaired in inflammatory bowel disease, and certain aspects, including toxic oxygen metabolite production, are enhanced in circulating monocytes and tissue phagocytes isolated from the inflammatory site. 5-Amino-salicylic acid, used in the treatment of inflammatory bowel disease, is a specific scavenger of hypochlorite, a toxic metabolite of oxygen produced by phagocytic cells. These findings suggest that phagocytic cells play an important role in the pathogenesis of tissue damage in inflammatory bowel disease. The future development of pharmacological agents which modify specific aspects of phagocyte function, or act as scavengers of toxic oxygen metabolites produced by these cells, may provide more effective treatment for these conditions.