Enhancement of adaptive immune responses of aged mice by dietary intake of β-glucans, with special emphasis on anti-aging activity.

The naturally occurring polysaccharide, β-1,3-glucans, a well-known immunostimulant, has been highly valued for many years for their health-promoting and anti-aging properties, but its mode of action is poorly understood. In this study, we first showed that oral administration of β-1,3-glucans did not affect the general condition and physiology of male mice throughout the trial period. We then showed that dietary intake of β-1,3-glucans induced a significant increase in T helper cells (CD4+) in young, middle-aged and aged male mice. We also showed that β-1,3-glucans supplementation considerably increased the delayed-type hypersensitivity (DTH) response, a T cell-mediated immune response, in young and aged mice. In addition, we found that β-1,3-glucans supplementation remarkably promoted the production of total anti-keyhole limpet hemocyanin (KLH) immunoglobulin G (IgG), anti-KLH IgG1, and anti-KLH IgG2a in young and aged mice without disturbing immune homeostasis. These data together indicate that oral administration of β-1,3-glucans enhanced the adaptive immune responses of aged mice without disturbing their general condition and physiology, supporting the idea that β-1,3-glucans are capable of counteracting the immunosenescence in mice. They also suggest that β-1,3-glucans can be clinically useful to help the elderly generate an improved response to vaccine with stronger humoral and cell-mediated immune responses.