Interactions of epigallo-catechin 3-gallate and ovalbumin, the major allergen of egg white

•The major green tea catechin, EGCG, interacts with the major dietary protein, OVA.•The binding of EGCG to OVA induces conformational changes in the protein.•The EGCG-binding pocket in OVA partly overlaps with the known IgE-binding epitopes.•The OVA/EGCG complex binds IgE and stimulates basophil degranulation.•The EGCG binding to OVA might modulate other cellular processes. Polyphenols, the potent plant secondary metabolites, have beneficial effects on human health, but the mechanism(s) by which these effects are exerted is not well understood. Here, we present the detailed analysis of the interactions between the major green tea catechin, epigallo-catechin 3-gallate (EGCG), and the major dietary protein and allergen, ovalbumin (OVA). We show that EGCG binds to the pocket that partly overlaps with the previously identified IgE-binding region in OVA, and that this interaction induces structural changes in the allergen. Moreover, our ex vivo studies reveal that OVA binds IgE and stimulates degranulation of basophils, and that its uptake by monocytes proceeds at a slower rate in the presence of EGCG. This study provides further evidence in support of the proposed mechanism by which EGCG interactions with the food allergens contribute to its diverse biological activities and may impair antigen uptake by antigen-presenting cells.