A novel and sensitive method for the detection of T cell stimulatory epitopes of α/β- and γ-gliadin

Background: It is now generally accepted that coeliac disease (CD) is caused by inflammatory T cell responses to gluten peptides bound to HLA-DQ2 or -DQ8 molecules. There is overwhelming evidence that CD patients can mount T cell responses to peptides found in both α-gliadin and γ-gliadin molecules. Assays that would detect the presence or absence of such peptides in food would thus be accurate indicators of safety for consumption by CD patients. Aims: The development of a sensitive method to detect T cell stimulatory epitopes of α-gliadin and γ-gliadin molecules in food products. Methods: Monoclonal antibodies (mAb) were raised against peptides encoding the T cell stimulatory epitopes of α-gliadin (amino acids (aa) 59–71) and aa γ-gliadin (aa 142–153 and aa 147–159). These mAb competition assays were developed that quantitatively detect T cell stimulatory epitopes present on both intact proteins and peptides of sizes recognisable by CD4+ T cells. Results: With the mAb based competition assays, T cell epitopes were detected in pepsin/trypsin digests of wheat proteins and ethanol extracts of various food products, with detection levels lower than those reached with gluten specific T cells. Moreover, the presence of T cell stimulatory epitopes was also detected in preparations of barley, rye, and triticale, other cereals known to be toxic for CD patients. Conclusions: A new antibody based method has been developed, detecting the presence of T cell stimulatory gluten peptides. This can be used to further ensure the safety of food consumed by CD patients.