Comparative study of immune-enhancing activity of crude and mannoprotein-free yeast-glucan preparations

초록

beta-Glucan, one of the major cell wall components of Saccharomyces cerevisiae, is known to enhance the immune function, especially by activating macrophages. Accordingly, in an effort to develop a safe and efficient immune stimulatory agent, we prepared crude beta-glucan (glucan-p1) and partially purified beta-glucan that was free of mannoproteins iglucan-p2), and evaluated their effect on both the macrophage function and resistance to E. coli-induced peritonitis. To investigate the function of the macrophages, phagocytosis, TNF-alpha secretion, oxygen burst, and the expression of cytokine genes such as TFN-gamma and IL-12 were analyzed. Glucan-p2 markedly stimulated the macrophages with all these parameters. Glucan-p1, however, did not stimulate phagocytosis, yet it induced TNF-alpha secretion, oxygen burst, and the expression of IFN-gamma and IL-12, aid-tough less efficiently than glucan-p2. Finally, to test the in vivo protective effect of beta-glucan against infection, the survival of mice from E. coli-induced peritonitis was investigated. After 24 h of the peritoneal challenge of E. coli, all of the mice treated with glucan-p2 survived whereas none survived in the control group. Glucan-p1 showed only a marginal effect in protecting the mice. These results suggest that mannoprotein-free glucan-p2, but not glucan-p1, can serve as an effective immune-stimulating agent.

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