CELL-MEDIATED-IMMUNITY AND MUCOSAL IMMUNITY

Studies of intraepithelial lymphocytes have shown that these cells have specialized characteristics and functions. Although their function is uncertain in vivo, they appear to have the potential to function as regulatory or cytolytic cells in response to a limited array of antigens. There have been no convincing abnormalities of these cells in inflammatory bowel disease (IBD). The most important advance in basic immunology in IBD has been the observation of spontaneous colitis or enterocolitis in mice having experimentally induced genetic deficiencies of cytokines or T-cell receptors. Further studies in human IBD have shown that there are some differences in the cytokine profile in Crohn's disease and ulcerative colitis, consistent with differences in underlying pathogenesis. Adhesion molecules are important for entry of lymphoid cells into sites of inflammation and may serve as potential targets for immunotherapy in IBD. The relevance of antineutrophil antibodies to the pathogenesis of IBD remains unclear. Further work suggests that IBD may be associated with HLA genes. One potential colon epithelial cell autoantigen has been identified in ulcerative colitis.