Mapping and Mutational Analysis of the IgE‐Binding Epitopes on Ara h 1, a Legume Vicilin Protein and a Major Allergen in Peanut Hypersensitivity

TLDR

Peanut allergy poses a major health risk due to its prevalence and potential severity. The study aims to map core amino acids in Ara h 1 epitopes to clarify peanut hypersensitivity mechanisms. The authors used patient IgE and overlapping peptides to map Ara h 1 IgE‑binding epitopes. They identified 23 linear IgE‑binding epitopes on Ara h 1, including four immunodominant sites recognized by >80 % of patients, and showed that single amino acid changes in these sites dramatically altered IgE binding.

Abstract

Peanut allergy is a significant health problem because of the prevelance and potential severity of the allergic reaction. Serum IgE from patients with documented peanut hypersensitivity reactions and overlapping peptides were used to identify the IgE‐binding epitopes on the major peanut allergen, Ara h 1. At least twenty‐three different linear IgE‐binding epitopes, located throughout the length of the Ara h 1 protein, were identified. All of the epitopes were 6–10 amino acids in length, but there was no obvious sequence motif shared by all peptides. Four of the peptides appeared to be immunodominant IgE‐binding epitopes in that they were recognized by serum from more than 80% of the patients tested and bound more IgE than any of the other Ara h 1 epitopes. Mutational analysis of the immunodominant epitopes revealed that single amino acid changes within these peptides had dramatic effects on IgE‐binding characteristics. The identification and determination of the IgE‐binding capabilities of core amino acids in epitopes on the Ara h 1 protein will make it possible to address the pathophysiologic and immunologic mechanisms regarding peanut hypersensitivity reactions specifically and food hypersensitivity in general.