AN INNOVATIVE SANDWICH ELISA SYSTEM BASED ON AN ANTIBODY COCKTAIL FORGLUTEN ANALYSIS

A cocktail sandwich ELISA based on the employ of two monoclonal antibo dies (MAbs) as coating antibodies and a third MAb conjugated to horser adish peroxidase has been developed for the analysis of gluten in food s. Given that each MAb displays a wide specificity spectrum for wheat, barley, rye and oats prolamins, their combination for ELISA ensures a high crossreactivity with most of the potentially toxic gliadin, hord ein, secalin and avenin protein family, One of the unprecedented featu res of the cocktail sandwich ELISA is that it permits for the first ti me analysis of barley hordeins in foods, which is unattainable using c onventional or commercial ELISA kits. Besides, gliadins, hordeins and secalins are recognised to the same extent. The system provides a high detection sensitivity for gliadins, hordeins, secalins and avenins (1 .5, 0.05, 0.15 and 12 ng/ml, respectively). The working linear range c omprises 3-100 ng/ml with a gliadin detection limit of 1.5 ppm. This l imit of detection is even better than that demanded in the latest Code r recommendation, 10 ppm. Cocktail ELISA data were contrasted with tho se of commercial ELISA kits and confirmed by mass spectrometry, a non- immunological technique which provides evidence for the occurrence of false positive results with the commercial kits, (C) 1998 Federation o f European Biochemical Societies.