Soybean beta-conglycinin-induced gut hypersensitivity reaction in a piglet model

Soybean is a major protein source in human and animal nutrition, but has also been described as a source of allergenic reactions. The objective of this study was to investigate anaphylactic reactions induced by purified soybean beta-conglycinin in 10-day old piglets, and to elaborate the molecular and cellular mechanisms of intestinal injury resulting from soybean hypersensitivity. We investigated the oral allergy syndrome and anaphylactic reactions in piglets caused by soybean beta-conglycinin with an intragastric feeding protocol without using an adjuvant. Physical symptoms, including lethargy, diarrhoea and respiratory distress were monitored to determine the anaphylactic reactions. Immunological assessment was conducted through measurement of immunoglobulin E (IgE) antibody concentration. Jejunal tissue was assessed for morphologic changes after the oral challenge, and histamine release, mRNA expression and endogenous production of cytokines were analysed. The results showed that beta-conglycinin reduced growth of piglets, and after oral challenge, sensitised piglets displayed signs of allergic hypersensitivity. Furthermore, the levels of both total IgE and antigen-specific IgE in the sera were increased. Histological examination of jejunum revealed intestinal morphology damage, higher levels of interleukin-4, interferon-gamma and significant levels of histamine were detected in the tissues. Our results indicate that purified beta-conglycinin possesses intrinsic immune-stimulating capacity and can induce an allergic reaction, which was IgE mediated. Both T helper2 and T helper1 responses may play important roles in the intestinal injury resulting from soybean hypersensitivity.