42. EXPRESSION OF CLASS II MHC ANTIGENS IN THE INTESTINAL EPITHELIUM OF PAEDIATRIC COELIAC DISEASE (CD)

Since CD of the infancy has been found to be associated with products of HLA-B, -DR, and -DQ loci of MHC, the expression of class II antigens in the intestinal mucosa of 16 children with CD, diagnosed according to ESPGAN criteria (4 m. and 12 f., aged 11 mos.- 14 yrs.) was evaluated immunohistochemically. Biopsy specimens were obtained from patients on gluten-containing diet, showing subtotal mucosal atrophy (8 patients), and on gluten-free diet with normal mucosa (10 patients). Control normal specimens were obtained from biopsies performed in 5 subjects with food allergy or other non inflammatory diseases. 4 microns acetone fixed cryostat sections were stained by indirect immunofluorescence and peroxidase with monoclonal antibodies to non polymorphic determinants of HLA-DR, -DP, and -DQ antigens. The results of the study showed that DR antigens are expressed in 100% of the cases, whereas no detectable levels of DQ antigens were found. DP antigens were demonstrable in 44% of the biopsies of coeliac subjects, without changes related to the diet; on the contrary, no DP antigen expression was found in the control group. Present findings suggest that the pattern of expression of class II MHC antigens in the intestinal epithelium of coeliac children does not show any relationship to the diet. No differences could be drawn between cases and controls, with the only exception of DP expression. This is evident in about the half of coeliac patients. Supported by CNR P.F. “Ingegneria Genetica - Basi Molecolari delle Malattie Ereditarie”, contr. n. 85.01421.51