[Immunohistochemical study of HLA-DR expression in superficial epithelium and in lamina propria of colonic mucosa in children with Crohn's disease and nonspecific ulcerative colitis].

Some researches have stressed the importance of expression HLA-DR on the superficial epithelium and on the lamina propria of the colonic mucosa of patients with ulcerative colitis and Crohn disease. In this research the histological characteristics of the expression HLA-DR on the resident mucosa of both these illness were quantified and analysed. Twelve Crohn disease, 19 ulcerative colitis and 10 specimen of the rectal mucosa, representing the control group according to the following model were studied: I period = pre-treatment, II period = up two years of evolution and III period = more than two years of treatment. The expression HLA-DR was identified by the monoclonal HLA-DR (DAKO) in the resident mucosa specimen by the immunoperoxidase method. The quantification of the expression HLA-DR on the lamina propria was done through the chromatic computer images analysis that express the area (micron2) used by the positive HLA-DR cells and the superficial epithelium in percentage by a semi quantifier evaluation. On the lamina propria of the illness mucosa, the expression HLA-DR was increased in all the studied periods when compared with the control group, but without statistics differences. The distribution of the expression HLA-DR on the lamina propria was done to the corresponding localization to the macrophages and to the B lymphocytes. The superficial colonial epithelium of the ulcerative colitis and Crohn disease patients was in 86.95% and in 80.96% respectively HLA-DR positive in the three periods. The superficial epithelium of all the rectal mucosa of the control group did not show the HLA-DR expression. The presence of the HLA-DR expression on the superficial colonial epithelium of the ulcerative colitis and Crohn disease patients and its absence in the control group was a very important found in this research. It is a consense among several authors that the HLA-DR expression represents a intense local action of the inductorious cytokines of this expression in the colonic mucosa of the ulcerative colitis and Crohn disease patients, representing its activation in a answer to the invasor antigen in the intestinal mucosa. The study of the HLA-DR expression in the lamina propria was not conclusive, because the result did not represent a significative difference in relation with the control.