Dietary supplementation with mushroom-derived protein-bound glucan does not enhance immune function in young and old mice.

Decline in immune response is a well-documented age-associated biological change. Protein-bound polysaccharides (PSP) are biological response modifiers and have been shown to have immunoenhancing and antitumor effects. This study was conducted to examine the effect of dietary supplementation with PSP-containing extract derived from mycelia of Coriolus versicolor on in vitro and in vivo indices of immune function of young and old mice. Young (5 mo) and old (23 mo) C57BL/6NIA mice were fed purified diets containing 0, 0.1, 0.5 or 1.0% PSP for 1 mo at which time indices of immune function were measured. PSP supplementation had no significant effect on mitogenic response to concanavalin A (Con A), phytohemagglutinin (PHA) or lipopolysaccharide (LPS), or on production of interleukin (IL)-1, IL-2, IL- 4 and prostaglandin E2 (PGE2). Of the in vivo indices of immune function tested, old mice fed 1.0% PSP had significantly higher delayed-type hypersensitivity (DTH) response than those fed 0% PSP. No significant effect of PSP was observed on the DTH response of young mice. The antibody response to sheep red blood cells was not significantly influenced by PSP in young or old mice. These results suggest that PSP-containing extract from mycelia of Coriolus versicolor might have a modest immunoenhancing effect in aged mice, but not in young mice.