Macrophages of the mammalian small intestine: a review.

Abstract

The present review resulted from questions concerning the fate in the intestine of ingested particulate pollutants such as asbestos and fly ash. These and other similar particulates are common contaminants of food and water, but little is known of the hazards associated with their ingestion. It is probable that they present some hazard if they penetrate the intestinal mucosa. In a recent study, fly ash from a coal-burning power plant was found to contain both organic and inorganic mutagens (34). The dangers of asbestos ingestion have been widely discussed (20, 36a, 41, 56, 83, 100, 148, 172, 184), although the extent of asbestos penetration of the intestinal mucosa still uncertain (20, 69, 108, 181). It seemed obvious that many of the particulate pollutants which penetrated the mucosal barrier would be phagocytized by macrophages residing in the lamina propria and that a study of the disposition of particulates within the gut wall should begin with a consideration of intestinal macrophages of lung, pertoneal cavity, spleen and liver have been discussed at length (25), little published work has dealt directly with the origin, abundance and activities of intestinal macrophages. Nevertheless, considerable information on intestinal macrophages and their interactions with materials which reachmore » them from the intestinal lumen is available in publications dealing primarily with other topics. Such information is important in toxicologic studies as well as in studies of host defences to intestinal Ags. It is, therefore, appropriate to assemble and discuss findings on intestinal macrophages, even though at present more questions will be raised than can be answered.« less