Effect of Phytic Acid on IgE Binding to Peanut Allergens

Abstract

RATIONALE: Phytic acid is a peanut component with 6 phosphate groups. Our preliminary studies indicated that it binds to peanut major allergens. Our objective was to determine if phytic acid-bound peanut allergens are different from native allergens in IgE binding. METHODS: Two different methods of plate preparation were used for the indirect ELISA. In the first method, a peanut protein extract was first treated with phytic acid (2 mM), centrifuged, and discarded. The resultant pellets (containing the phytic-acid bound allergens) were then diluted with 0.1 M sodium bicarbonate buffer, pH 9 for plate coating. In the second method, the plate was coated with the extract, followed by the addition of phytic acid. A control plate was performed by coating the plate with a phytic acid-free extract. A pooled serum (IgE antibodies) from five peanut-allergic individuals was then added, and detected colorimetrically, using a rabbit anti-human IgE peroxidase conjugate and a substrate of o-phenylenediamine. RESULTS: Plates coated with phytic acid-bound peanut allergens (prepared from the above two methods) appeared to exhibit the same level of IgE binding as the control plate. This suggests that phytic acid did not affect IgE binding or the allergenic properties of peanut allergens. CONCLUSIONS: Phytic acid appears to have no effect on the allergenic properties of peanut allergens, based on the finding that phytic acid-bound allergens were not differrent from the native allergens in IgE binding. This suggests that peanut components such as phytic acid may not have a role in the allergenic properties of peanut allergens.