Identification of common released peptide and allergenic cross-reactivity of protein fractions among cereals

Cross-reactivity between wheat and related cereals is a clinically relevant phenomenon, potentially driven by conserved digestion-resistant peptides. In this study, proteins extracted from wheat, barley, and rye were subjected to in vitro digestion and assessed by indirect enzyme-linked immunosorbent assay (ELISA) and competitive ELISA, using sera from wheat-allergic patients immunized mice, respectively. Peptides released during simulated digestion were analyzed by mass spectrometry, and the potential allergenicity of the cereals was evaluated using cell lines. Results showed high cross-reactivity among wheat, barley and rye, evidenced by strong specific IgG/IgE-binding abilities and similar degranulation capacities. Notably, the peptide "PQQPFP", which matches known wheat gliadin epitopes, was detected in all digested samples during different digestion times. This peptide may contribute to the observed cross-reactivity among these cereals. The molecular basis of cereal cross-reactivity is elucidated from digestive peptides, providing theoretical support for high-throughput screening of cereal-based foods.