Soybean glycinin- and β-conglycinin-induced intestinal immune responses in a murine model of allergy (1)
Glycinin and b-conglycinin are the two major storage proteins in soybean, constituting approximately 40% of the total seed protein.
Three of the glycinin-sensitised mice and four of the β-conglycinin-sensitised mice showed diarrhoea symptoms. The symptom appeared two days after oral sensitisation and lasted for less than five days. Noticeable histological changes were observed with decreased villous height and thickened crypt depth in the glycinin- and β-conglycinin-sensitised mice compared to the control. The jejunal histamine levels were increased in mice sensitised with glycinin and β-conglycinin compared with the saline-treated mice.
Numbers of IgA+B cells and CD4+T cells were increased in the mice sensitised with glycinin or β-conglycinin.
The intestinal IgA levels in the sensitised mice were increased compared with those of the control group (0.27 µg/mg and 0.37 µg/mg, respectively).
mRNA levels of IL-4 and IFN-γ were increased in the mice sensitised with glycinin and β-conglycinin, whereas levels of IL-10 and TGF-β mRNA expression were decreased.
IgE and IgG1 were involved in the allergic reactions of Balb/c mice. These antibodies activate mast cells, resulting in an excessive release of histamine, which may contribute to the intestinal damage and diarrhoea. The intestinal damage allows antigens to pass rapidly into the systemic circulation and induces specific mediator release. a significantly increased histamine level resulting from mast cell degranulation after antigen challenge in the sensitised animals. IL-4 and IFN-γ produced in spleen cells may play important roles in systemic immune responses to glycinin and β-conglycinin in sensitised mice. TGF-β and IL-10 play a central role in mucosal immunity. TGF-β inhibits the proliferation of naive T cells, whereas IL-10 blocks antigen presentation and T cell activation; thus, they both function as immunosuppressive cytokines. The soybean protein-induced local immune responses could be associated with cytokine production and lymphocyte differentiation in the MLN. Jejunum might be the main gut site in which allergen sensitisation occurs. Several studies have used jejunum to investigate the immune responses after exposure to allergenic food antigens.