Expression of class II MHC antigens in the intestinal epithelium of pediatric celiac disease.

Class II MHC antigen expression in the intestinal epithelium of 28 small bowel biopsies from 23 celiac patients were studied by means of indirect immunofluorescence and immunoperoxidase using monoclonal antibodies. Patients were divided on the basis of diet into two subgroups: 15 subjects on a gluten-containing diet (GCD) and 13 on a gluten-free diet (GFD). The control group included 10 pediatric subjects with normal intestinal mucosa who underwent intestinal biopsy for chronic diarrhea or short stature. DR antigens and invariant chain were expressed in all patients, regardless of the diet, as well as in the control subjects. DQ was found in one patient only on GCD. DP antigens were present in 12/15 patients on GCD, and in 2/13 on GFD (Fisher's exact test, p = 8.8 x 10(-4), as well as in 3/10 control subjects. In 4/5 celiac patients, DP antigens, which were undetectable on GFD, could be demonstrated after gluten challenge. The results of the study show that DR antigens are expressed by intestinal mucosa of celiac patients independently of their gluten exposure and that DQ antigens are consistently undetectable. Statistically significant differences in expression of DP antigens on enterocytes of celiac patients on GCD and their neoexpression after gluten challenge may represent a basis for further investigation.