Purification of soybean cupins and comparison of IgE binding with peanut allergens in a population of allergic subjects

Identification, purification and characterization of allergens is crucial to the understanding of IgE-mediated disease. Immunologic and structural studies with purified allergens is essential for understanding relative immunogenicity and cross-reactivity. In this work, the complex soybean 7S vicilins (Gly m 5) with three subunits and 11S legumins (Gly m 6) with five subunits were purified and characterized along with purified peanut allergens (Ara h 1, 2, 3, and 6) by label-free liquid chromatography-tandem mass spectrometry (LC-MS/MS). Individual subjects plasma IgE binding was tested from subjects allergic to soybeans and or peanuts by immunoblotting, ImmunoCAP™ and ISAC™ ImmunoCAP chip, comparing these soybean proteins with those of purified peanut allergens; vicilin (Ara h 1), 2S albumin (Ara h 2 and Ara h 6) and 11S globulin (Ara h 3). Results show differences between methods and subjects demonstrating the complexity of finding answers to questions of cross-reactivity.