In vitro and in vivo immunomodulating activities of Shoyu polysaccharides from soy sauce.

We investigated the effects of Shoyu polysaccharides (SPS) prepared from soy sauce on immune functions in mice. SPS enhanced the consumption of glucose by peritoneal macrophages in vitro. In addition, oral administration of SPS to 6-week-old male BALB/c mice for 2 weeks at a dose of 3.0 mg/day increased the capacity of peritoneal macrophages to consume glucose as compared to control mice. We observed the regulatory effect of SPS on the balance of Th1/Th2 cell responses in mice. In splenic lymphocytes stimulated with Con A in vitro, SPS significantly suppressed the production of IL-4 and enhanced that of IFN-gamma. Furthermore, in mice treated with SPS at 3.0 mg per day for 2 weeks, the balance of Th1/Th2 cell responses was shifted to predominantly Th1 cell responses. These findings suggest that SPS effectively enhanced both macrophage and lymphocyte function in vitro and in vivo, and soy sauce would be a potentially promising food for enhancing host defenses.