Preparation of goat milk anti-Saccharomyces cerevisiae immunoglobulin G (IgG)-rich fraction and immunological functions of mice orally administered a mixture of the antigen and its specific IgG-rich fraction

In the current study, we investigated the effects of Saccharomyces (S.) cerevisiae and its specific immunoglobulin G-rich fraction (anti-yeast IgG) prepared from goat's milk on the mouse immune system. Real-time polymerase chain reaction (PCR) analysis of mRNA extracted from C3H/HeN mouse Peyer's patch cells revealed that the expression of Rnf128 on regulatory T cells was higher in the cells cultured with anti-yeast IgG alone or with a mixture of S. cerevisiae and anti-yeast IgG than in the cells cultured with S. cerevisiae alone. In contrast, the expression of Stat6 related to polarize type 2 helper T (Th2) cells was lower in the cells cultured with the mixture than S. cerevisiae alone, although that was higher than IgG alone. Hence,5-week-old C3H/HeN mice were orally administered with either saline solution (control) group or a mixture of S. cerevisiae and anti-yeast IgG in saline (test) group once a day for 5 weeks. We found total serum IgG levels to be significantly lower in mice administered the test solution than those that were given the control solution. Microarray analysis of mRNA extracted from the mouse Peyer's patch cells revealed that the expression profile of genes related to proliferation and differentiation of B cells, T cell activation and differentiation of Th2 cells was lower in the test mice than in the control group. In contrast, the genes related to regulatory T cells were more highly expressed in mice administered with the test solution. Moreover, oral administration of the test solution was found to reduce allergic symptoms in NC/Nga mice induced with a mite antigen. The number of spleen interleukin-4sup(+)CD4sup(+) cells was reduced in test mice when compared to the control group. These findings indicate that oral administration of the mixture of S. cerevisiae and its specific goat milk IgG-rich fraction may suppress the development of type I allergic symptoms in mice.