Role of bile in non-specific defence mechanisms of the gut.

The effect of depriving the intestine of bile for 48 hours was studied to determine any influence on various parameters of innate immunity in the gastrointestinal tract. Groups of rats were prepared by bile duct cannulation (with or without fluid replacement) or bile duct ligation. Normal and sham operated animals were used for comparing the thickness of the mucus layer and the cells contained therein, enumeration of goblet cells, and measurement of villus size. Histological examination indicated that the intestinal tissues of treated and control rats were similar. Though villus size and numbers of goblet cells were unaffected, a significant reduction occurred in the thickness of the mucus blanket in the duodenal regions of rats deprived of bile, and there were significantly lower numbers of mucus associated enterocytes and lymphocytes, suggesting a lower turnover rate of the epithelium. The balance of the bacterial populations in the caecum and intestine was altered by bile deprivation-increased numbers of coliform organisms were found in both regions. The range of factors, including antibodies and other known constituents, present in bile may contribute to the maintenance of tissue integrity and influence the balance in indigenous bacterial populations in the intestine. Disturbance of the host's biliary system and concomitant effects on the microbial flora may weaken the overall processes of defence in the intestine.