The Possible Role of Effector Cells on the Intestinal Mucosa and Gastrointestinal Host Defenses in Intractable Diarrhea

The defense of the gastrointestinal (GI) tract against potentially harmful organisms requires the concerted and integrated functions of diverse host defense mechanisms, both physiologic and immunologic. Recently, we have begun to appreciate that a wide variety of immunologic effector cells are located in the GI mucosa and that it should be possible to manipulate their activities to the benefit of the host. This chapter addresses our understanding of immunologic effector cell function in the intestinal mucosa and the potential ways in which we may influence such immune activities for host defense. For more detailed discussions of our concepts of immunity in the intestine and other mucosal sites, we refer the reader elsewhere (1-6). Since little is known about GI immunity in intractable diarrhea and the effector components of immunity that may play a role in the development and maintenance of this condition, we have offered some examples of mucosal effector cell function and alteration in regard to other types of GI disease. Our understanding of such effector activities may well be applicable to intractable diarrhea.