Absorption and presentation of antigens by epithelial cells of the small intestine: hypotheses and predictions relating to the pathogenesis of coeliac disease.

Effects of the route of antigen absorption and presentation in the small intestine are discussed in relation to outcomes from antigen exposure. It is proposed that antigens presented by epithelial cells to intrinsic T cell populations in the mucosa induce anti-inflammatory immune responses, while antigens presented to conventional T cells by lamina propria APC predisposes to inflammation. The pathogenesis of coeliac disease is attributed to three factors: a defect in antigen processing by epithelial cells; the intrinsic properties of the gliadins; and the HLA-D haplotype of the individual. It is suggested that MHC class II molecules play a role in antigen uptake by enterocytes, in addition to their function in antigen presentation to T cells.