Mechanisms of intestinal epithelial cell injury and colitis in interleukin 2 (IL2)-deficient mice.

Epithelial cell (EC) injury is a feature of all inflammatory bowel disorders (IBD). Although the mechanisms of EC injury are incompletely understood, it has been proposed that T-cell-mediated cytotoxicity and production of inflammatory cytokines are involved. This hypothesis was tested using the interleukin 2-deficient (IL2-/-) mouse model of IBD and cultures of primary colonic EC to determine if abnormal cytokine production or cytotoxicity by colonic T cells cause EC injury. Although capable of cell-mediated killing of allogeneic target cells, IL2-/- colonic T cells were unable to lyse syngeneic colonic EC. During disease progression, large numbers of IL4, TNF-alpha, and IFN-gamma-producing CD4+ and CD8+ cells accumulated within the intraepithelial spaces and lamina propria of the colon of IL2-/- mice. Although colonic EC expressed receptors for IFN-gamma and TNF-alpha, these cytokines did not adversely affect EC viability or growth in vitro consistent with these cytokines not being the primary mediators of EC injury in IBD. Our novel colonic EC culture system provides an in vitro accessible system in which to investigate further the nature of EC-lymphocyte interactions.