A Sandwich Enzyme-Linked Immunosorbent Assay (ELISA) for the Quantitation of Selected Peanut Proteins in Foods

Abstract

A sandwich-type, enzyme-linked immunosorbent assay (ELISA) was developed for the detection of selected peanut proteins in foods. Monoclonal antibodies against a series of allergenic peanut proteins were used as the capture antibody. Food sample extracts were then added, and polyclonal rabbit antibodies directed against roasted peanut proteins were employed as secondary antibodies. The amount of allergen bound to the solid-phase was determined by a biotin and streptavidin-peroxidase system. Radioallergosorbent assay (RAST) inhibition studies of the food extracts were done as a comparison. The coefficient of determination for the ELISA and RAST assays was 0.85. Selected food samples were tested by RAST inhibition at another laboratory for comparison. Skin tests were done with selected samples in peanut-allergic adults, and the results correlated to the ELISA and RAST inhibition results. In other studies, defatted peanut protein (0.01 to 5.0%) were added to vanilla ice cream, then extracted and analyzed using ELISA and skin tests. The sensitivity of the ELISA in ice cream was approximately 40 μg/ml. In six of seven peanut-sensitive adults tested, the lowest level of added peanut protein (0.01%, 21 μg/ml) still caused a positive skin test reaction.