GLIADIN ACTIVATES MUCOSAL CELL-MEDIATED IMMUNITY IN IN VITRO CULTURED RECTAL MUCOSA FROM COELIAC PATIENTS AND A SUBSET OF THEIR SIBLINGS

Abstract

An increment in CD3+ and γδ+ cells in the rectal mucosa has been reported after local instillation of gluten in children with coeliac disease and in half of their siblings. Aim of this study was to establish an in vitro system to fully assess immunological changes induced by gluten in the rectal mucosa. Rectal biopsy specimens were obtained from 11 children with treated coeliac disease, 9 controls and 8 siblings of coeliac children, and in vitro cultured for 24 hours in the presence of 1 mg/ml of a peptic-tryptic digest of gliadin (PT) or ovalbumin (OVA) as control protein. At the end of the culture, biopsies were snap frozen and an immunohistochemical analysis carried out. CD3+ and CD25+ cells were counted and the expression of adhesion molecules ICAM1, ELAM1, VCAM1 also evaluated. In the lamina propria of coeliac biopsies cultured in the presence of PT, but not in those from controls, the expression of VCAM1 molecules was enhanced, and the number of CD25+ cells (mean±SD: 413±142/mm2) significantly (p<0.001; paired t test) higher than in biopsies cultured in medium alone (206±88); also the density of intraepithelial CD3+ cells was significantly higher (19.6±10.2/100 epithelial cells vs 10.8±5.8; p<0.05). No differences were noted in coeliac biopsies cultured with OVA. A discriminant analysis of immunohistochemical data allowed correct classification of 100% coeliacs. 4 out of 8 siblings (50%) were also allocated in the coeliac group. In conclusion, our data confirm that gliadin is able to activate mucosal cell-mediated immunity in the rectal mucosa in coeliac patients, and in a subset of their first-degree relatives. The ease of access and the validation of such in vitro system render the rectal mucosa particularly suitable to study immunogenicity of cereal proteins and peptides and to screen gluten-sensitive subjects.