Immunochemical analysis of oat avenins in an oat cultivar and landrace collection

Oats have been found to be tolerated by most celiac disease patients, and oats are generally considered a good and safe addition to the gluten-free diet. There have been claims that some individual oat cultivars are harmful or immunogenic for celiac disease patients. In this study, we investigated 26 oat cultivars and landraces from the current breeding market and literature. Their total protein content ranged from 15.3% to 23.1% of which avenins ranged from 6.8% to 10.9%. Immunological activities of avenins were evaluated using immunochemical analyses using monoclonal antibodies (mAb) R5 and G12. No immunological activity of the oat cultivars was observed by mAb R5 either in immunoblotting or enzyme-linked immunosorbent assay (ELISA). mAB G12 showed no activity in immunoblotting, but gave responses between 13 and 53 mg/kg in ELISA for total avenin extract. To understand the varying G12 activity, avenins were further fractionated. One avenin fraction showed a higher G12 response than the other fractions. Protein sequence comparison suggests that there is no direct binding to avenin-specific T-cell epitopes but the differences in repetitive regions in avenins may contribute to varying results in G12 ELISA.