Background: Soybean hulls (SHs) cause respiratory allergies. This study investigates the allergenicity of soybean varieties (SVs) by in vivo and in vitro tests.
Methods: Ten SVs were studied: (a) five with a proved clinical relevance (SVs 1, 2, 3, 4, 5), the last four with a 'dull' phenotype; (b) five of undetermined relevance, three of them (SVs 6, 7, 8) with a 'shiny' phenotype, and two (SVs 9 and 10) with a 'dull' phenotype. Extracts from all 10 SVs were used to skin prick test (SPT) 21 subjects sensitized to SHs. Positive and negative sera pools prepared from sera of subjects sensitized or not to SHs, respectively, were utilized to perform in vitro experiments (specific IgE and IgG4 determinations, SDS-PAGE/IgE-Western blot, and IgE-inhibition).
Results: In this study, it was found that 52.4, 52.4, 57.1, 71.4, 80.9, 42.9, 57.1, 71.4, 52.4, and 38.1% subjects had a positive SPT with SVs 1-10, respectively (P NS). Specific IgE values to SVs 1-10 obtained with the positive pool are 28.3, 26.4, 29.9, 28.3, 26.8, 4.8, 13.4, 6.7, 24.7, and 17.5% total counts bound, respectively; and specific IgG4 values 0.851, 0.818, 0.721, 1.609, 0.789, 0.617, 0.662, 0.0, 1.127, and 0.934 OD units, respectively; the microgram of protein required to produce 50% inhibition are 2.5, 3.7, 4.5, 2.4, 5, 39.8, 25.2, 25.1, 4.5, and 8.9, respectively. A 7-kDa band is present in all SVs except in those with a 'shiny' phenotype.
Conclusions: The SVs with a 'shiny' phenotype contain less allergens than the other SVs studied, as determined by in vitro tests. However, SPT results with the SVs do not differ. Genetic screens should be devised to select plants with reduced, preferably absent, allergenicity, but with a high nutritional value, and this allergenicity should be studied utilizing in vivo and in vitro tests.