Role of soybean β-conglycinin subunits as potential dietary allergens in piglets.

β-Conglycinin, a major seed-storage protein in soybeans, is one of the primary antigenic proteins responsible for soybean-meal hypersensitivity in weaned piglets. The protein is a heterotrimer composed of subunits α, α' and β. It is currently unknown which of the β-conglycinin subunits are allergenic for piglets. The aim of this study was to identify potential allergenic subunits of β-conglycinin for soybean sensitive piglets and to characterise these subunits by immunoglobulin (Ig) G and E immunoblotting, ELISA, 'skin prick' and whole blood histamine-release testing. The IgG and IgE binding capabilities of the purified α, α' and β subunits of β-conglycinin were determined by immunoblot analysis and ELISA with sera from β-conglycinin sensitised piglets. Skin prick testing and whole blood histamine release testing were also performed to detect the activated effector cell response to specific allergens. Specific IgG and E antibodies were identified that recognised all three subunits of β-conglycinin in the sera of β-conglycinin sensitised piglets. All three subunits of β-conglycinin elicited positive skin test and specific histamine release responses from the whole blood of β-conglycinin sensitised piglets. These results suggest that all three β-conglycinin subunits are potential allergens for piglets.