Immunoglobulin E cross-reactivity between lupine conglutins and peanut allergens in serum of lupine-allergic individuals.

Background: Lupine is used increasingly in food products. The development of lupine allergy in peanut-allergic patients is believed to occur as a result of cross-reactivity between lupine and peanut proteins. Objective: To investigate the degree of immunoglobulin (Ig) E cross-reactivity between allergens in lupine and peanut. Methods: We investigated IgE cross-reactivity between lupine α-, s-, γ-, and δ-conglutins and the major peanut allergens Ara h 1, Ara h 2 and Ara h 3 using enzyme-linked immunosorbent assay with sera from patients with coexisting peanut and lupine allergy. Results: Peanut proteins inhibited IgE binding towards αconglutins, δ-conglutins, and, to a lesser degree, s-conglutins, while no IgE cross-reaction with δ-conglutin was observed. Ara h 2 most potently inhibited IgE binding to lupine and δ-conglutins, while Ara h 1 most potently cross-reacted with s-conglutin. Ara h 3 was apparently not involved in these mechanisms. Conclusions: The present study reveals IgE cross-reactivity between the 2S albumins Ara h 2 and δ-conglutin, and the 7S vicilin-like Ara h 1 and s-conglutin, which are possibly based on homologies between phylogenetically related proteins. Ara h 2 was the most potent inhibitor of IgE binding to lupine conglutins.