INTESTINAL EPITHELIAL-CELLS BOTH EXPRESS AND RESPOND TO INTERLEUKIN-15

Background & Aims: Interleukin (IL)-15 exerts functional effects on ly mphocytes similar to those of IL-2, IL-15 is expressed by nonlymphoid cells and may integrate these cells into classical immune responses, T he aim of this study was to characterize the expression of IL-15 by in testinal epithelial cells and determine the functional roles of IL-15 within the mucosal immune system. Methods: Rat IL-15 was cloned from a rat jejunal library, Expression of IL-15 in rat and human intestinal epithelial cells was assessed by Northern and Western blotting, Tyrosi ne kinase activation in response to IL-15 in intestinal epithelial cel ls was determined by immunoprecipitation, Results: Rat and human intes tinal epithelial cells express IL-15 messenger RNA, IL-15 activates St at3 and stimulates the proliferation of intestinal epithelial cells, T he relevance of the observations for intestinal epithelial cell functi on in vivo was supported by the demonstration of transcripts for IL-15 in primary human intestinal epithelial cells. Conclusions: IL-15 is e xpressed by intestinal epithelial cells and may be able to regulate in testinal epithelial cell function, These experiments suggest that IL-1 5 is an important mediator that could integrate intestinal epithelial cell function with the intestinal immune system.