EFFECT OF GLIADIN AND OTHER FOOD PEPTIDES ON EXPRESSION OF MHC CLASS-II MOLECULES BY HT-29 CELLS

Expression of major histocompatibility (MHC) class II molecules by ent erocytes is known to be enhanced in coeliac disease and other disorder s characterised by intestinal inflammation - an effect thought to be m ediated via intestinal lymphocytes. To investigate if food peptides ca n exert direct effects on class II expression, the influence of gliadi ns, casein, and beta lactoglobulin on an intestinal epithelial cell li ne (HT-29) was examined in the absence of immune cells. Class II expre ssion was determined by flow cytometry and immunofluorescence microsco py using antibodies against the beta chain of all products of the gene subregions DR, DQ, and DP. MHC expression was low in HT-29 cells but could be stimulated by interferon gamma. Tryptin digested gliadin had no effect on class II expression. In the presence of interferon gamma, however, it was able to amplify MHC class II expression to mean (SEM) 150 (4)%. Casein exerted a similar effect (160 (14)%), but undigested gliadin, tryptin digested casein, and beta lactoglobulin had no influ ence. The observations suggest that within the concert of cytokine med iated interactions between enterocytes and lymphocytes, some dietary p eptides could upregulate the presentation of food antigens, leading to a more efficient stimulation of lymphocytes, which in the case of coe liac disease might result in damage to the enterocytes.