Induction of major histocompatibility complex class II antigens on human colonic epithelium by interferon-gamma,...

Class II antigens are strongly expressed on the inflamed colonic epithelium in inflammatory bowel disease. However, the mechanism of this epithelial class II antigen induction is not fully understood. Increased activities of interferon (IFN)gamma, tumor necrosis factor (TNF)alpha, and interleukin (IL)2 have been shown in the inflamed mucosa of inflammatory bowel disease. Therefore, we studied whether these cytokines could induce class II antigens on the human colonic epithelium. By an organ culture technique, 284 normal colonic biopsy specimens obtained from 49 individuals were cultured in media containing different concentrations of cytokines with/without anti-IFNgamma R antibody. Colonic epithelial class II antigens were identified by the indirect immunoperoxidase staining method with anti-human leukocyte antigen (HLA)-DR, DP, and DQ monoclonal antibodies. IFNgamma, TNFalpha, and IL2 induced epithelial class II antigens in 16 of 16 cases (100%), 2 of 16 cases (12.5%), and 6 of 17 cases (35%), respectively. Epithelial class II antigen expression in response to TNFalpha was induced via IFNgamma but not via IL2. This is the first demonstration that: (i) the induction of class II antigens on the colonic epithelium in response to TNFalpha is mediated via IFNgamma, and (ii) that IL2 induces class II antigens.