Profiling Serum Antibodies with a Pan Allergen Phage Library Identifies Key Wheat Allergy Epitopes

Allergic reactions occur when IgE molecules become crosslinked by antigens such food proteins. The physiologic consequences range from mild to life-threatening. Here we create the ‘AllerScan’ bacteriophage display library for efficiently profiling allergic antibodies to characterize binding specificities associated with known allergens. AllerScan enables sensitive and unbiased characterization of circulating IgE and IgG antibody reactivities against thousands of allergenic proteins from hundreds of organisms at peptide resolution. Using AllerScan to analyze food allergy reactivities, we identify robust anti-wheat IgE reactivities in wheat allergic patients but not in wheat-sensitized individuals. Meanwhile, a wheat allergen epitope, alpha purothionin, elicits dominant IgE responses among allergic patients but frequent IgG responses among sensitized and non-allergic patients; a double-blind placebo-controlled trial shows that alpha purothionin reactivity, among others, is strongly modulated by oral immunotherapy. Our proof-of-principle results thus suggest that AllerScan to be a high-throughput platform for unbiased analysis of allergic antibody fine specificities.