Enzyme-linked immunosorbent assay for quantitation of cereal proteins toxic in coeliac disease

Coeliac disease is revealed by polypeptides in the prolamin fraction of wheat, barley, rye and oats. Recovery depends on adherence to a strict cereal-free diet. A few methods for quantitation of the wheat prolamin, gliadin, have been described. In order to assess the suitability of food products for inclusion in the coeliac diet an assay should measure the total amount of potentially toxic cereal proteins. An inhibition ELISA was developed, by use of a purified, polyclonal prolamin-antibody, reacting with gliadin and gliadin-like polypeptides. The antibody did not react with maize, millet, rice or soya prolamins. The assay had a detection limit of 1 ng antigen with a very high degree of accuracy. The interassay coefficient of variation including the day-to-day variation, was close to 30%, which is acceptable for the clinical applications of the assay. The flour of buckwheat was analyzed for antigen content. An amount of 39.5 micrograms gliadin-like polypeptides/g flour was measured, which corresponds to 0.06% of the gliadin content in wheat flour.