Expression of HLA-DR antigens on colonic epithelium around lymph follicles. An anomalous expression in Crohn's disease.

The relationship between the lymph follicle and expression of HLA-DR antigens on the colonic epithelium was investigated. Colonic specimens containing lymph follicles were examined immunohistochemically for HLA-DR expression. Thirty-six biopsy specimens (29 from macroscopically uninvolved areas and seven from aphthoid lesions) were obtained from 10 patients with Crohn's disease, and another 43 specimens were obtained from 33 patients with various intestinal diseases (non-Crohn's disease). HLA-DR antigens were expressed on the epithelium around the lymph follicle in both groups. However, the rate of expression (31/36) in Crohn's disease was significantly higher than that (5/43) in non-Crohn's diseases (P < 0.001). In addition, the extent and intensity of expression were broader and stronger in Crohn's disease than in non-Crohn's disease. This study is the first demonstration of anomalous HLA-DR expression on the epithelium around the lymph follicle in Crohn's disease.