Molecular characterization of wheat antigens involved in celiac disease

Abstract Wheat gliadins trigger a hypersensitive immune response in genetically susceptible individuals causing celiac disease (CD). The small intestinal mucosa of CD patients is characterised by presence of numerous infiltrating CD4+ T cells. These T cells proliferate and secrete IFN-γ when stimulated with gliadin extracts and are implicated in the mucosal damage and production of anti-gliadin antibodies. Peptide sequences in the Pro(P) and Glub(Q) rich regions of gliadins are known to be T cell-stimulatory but due to the heterogeneity of gliadin sequences, several potential stimulatory epitopes and the individual protein antigens are yet to be identified and characterized. Thus our aim was to identify and characterize wheat antigens with ability to initiate and sustain celiac disease. Due to their complex biochemistry the three subtypes of gliadins α/β, γ, and ω-gliadins are difficult to isolate into pure fractions. Hence, we developed a method wherein the alcohol extracted gliadins was sub-fractionated ion-exchange chromatography and each sub-fraction’s reactivity to serum IgA, from clinically well defined CD (active/diet) patients and non-CD patients was analyzed. We identified and generated recombinant gliadins that were CD specific. Epitope mapping studies revealed major immune-reactive regions. Recombinant gamma-gliadins will be useful for characterizing the immune response to wheat antigens and to develop reliable diagnostic and therapeutic strategies.