Characteristics of HLA II antigen expression in the rectal mucosa of children suffering form ulcerative colitis and Crohn disease

The staining of HLA class II. antigens was studied with monoclonal antibodies using sensitive immunohistochemical methods in the rectal biopsy specimens taken from 4 children with Crohn's disease and 9 with ulcerative colitis as well as from 10 controls. HLA class II. antigen expression was not seen in the surface and crypt epithelium of controls. The majority of patients showed epithelial HLA-DR, and HLA-DP expression, fewer had HLA-DQ expression. In patients who had more severe clinical and histological symptoms the epithelial HLA-DR and HLA-DP expression was more intense, than in those with milder presentation (p < 0.05). We conclude that the activity of ulcerative colitis may be infered from the intensity of HLA class II. antigen expression.