Is the Cross-Reactivity of Sin a 1, 2S Albumin from Mustard Seeds, Exclusively Restricted to Brassicaceae Members?

Food allergy is an important health problem that is gradually growing worldwide. The most prevalent food allergens are those of vegetal origin, affecting approximately 2-4% of the European adult population and 8% of childhood. 2S albumins have been described as relevant food allergens and their availability as purified molecules could constitute important clinical diagnostic advantage for food allergies. Despite the relatively low sequence similarity between members of this plant protein family, especially from distant species, studies focused on a potential role for these allergens in cross-reactivity and unexpected reactions have been approached. In this manuscript, different extracts from Brassicaceae family, tree nuts and other seeds have been isolated. Sin a 1, the 2S albumin from mustard seeds (Sinapis alba) and 2S albumin from pine nuts were purified and identified by mass-spectrometry. These proteins display typical features as their homologues from the 2S albumin family retaining the ability to bind IgE. Immunoblotting assays with a pool of Sin a 1-allergic patients’ sera revealed the allergenic capacity of members from the Brassicaceae family across the recognition of Sin a 1 and the IgE binding ability to pine nuts and sesame even though their different phylogenetic family. In conclusion, although cross-reactivity related to Sin a 1 is mainly assigned to Brassicaceae, other seeds, such as pine nut have to be keep in mind in order to unexpected reactions. These characterized allergens could be used as clinical tools elaborating a more accurate diagnosis and therefore a more effective allergy treatment.