Ganoderma tsugae mycelium enhances splenic natural killer cell activity and serum interferon production in mice

Effects of the water-soluble extract of Ganoderma tsugae mycelium (GT), its alcohol-insoluble subfraction (GTI), and its alcohol-soluble subfraction (GTS) on splenic natural killer (NK) cell activity and serum interferon (IFN) production were assessed in mice. Intraperitoneal administration of GT (4-200 mg/kg) or GTI (1-50 mg/kg), but not GTS, augmented the NK cytotoxic activity in a dose-dependent manner in C3H/HeN mice. This augmentation of splenic NK cytolytic activity was not mouse-strain-dependent. The serum IFN titers of mice were also elevated after i.p.-doses of GTI. The GTI-induced serum IFN was reduced by either IFN-(alpha+beta) antiserum or IFN-gamma monoclonal antibody in vitro. The treatment with antiserum neutralizing IFN-(alpha+beta) resulted in a 70% reduction of GTI-induced IFN, while monoclonal antibody against mouse IFN-gamma, moderately neutralized the GTI-induced IFN (50%). These results demonstrated that both the splenic NK activity and serum IFN [IFN-(alpha+beta) and IFN-gamma] titers are elevated by Ganoderma tsugae mycelium extracts in mice.