[Immunohistologic studies of differential HLA expression in patients with various intestinal diseases].

Histocompatibility antigens (HLA) play an important part in immunoregulation and in cell differentiation. This study analyses the expression of HLA class I and class II antigens (DR, DP, DQ) in intestinal biopsy specimen from patients with Crohn's disease, ulcerative colitis, GvHD, radiation colitis and intestinal adenomas using the indirect immunoperoxidase technique. 92 of 94 inflamed specimen from patients with inflammatory bowel disease showed a neoexpression of HLA II (DR greater than DP greater than DQ) on their epithelial cells. The intensity of HLA-DR neoexpression was significantly dependent on an endoscopic as well as a histological index of inflammation. All 75 non-inflamed specimen except 4 from patients with Crohn's disease did not show any evidence of HLA II display on the epithelium. 4 of 18 intestinal adenomas expressed HLA II on their epithelial cells without any correlation to the type of adenoma or the degree of cell dysplasia. Furthermore all specimen from a patient with intestinal GvHD showed an aberrant epithelial HLA II expression, but not that from radiation colitis. The expression of HLA class I antigens was similar in all biopsies studied. Our results suggest, that the epithelial neoexpression of HLA class II antigens may be an important event in the pathogenesis of various bowel diseases.