Mushroom-derived polysaccharides ($eta$-glucans) are considered as a valuable biopharmaceutical principle without displaying side effects. Although Tricholoma matsutake is well-known mushroom in Korea, Japan and China, the immunoregulatory roles of T. matsutake-derived polysaccharides were not fully elucidated yet. In this study, we continued to evaluate the immunomodulatory effect of T. matsutake-derived polysaccharide fraction (TmC-2) using functional activation models of macrophages, monocytes and splenic lymphocytes. TmC-2 treatment strongly increased the production of NO and TNF-$alpha$. Phagocytic uptake and ROS generation was also up-regulated by TmC-2. Interestingly, TmC-2 stimulated CD29-mediated cell-cell or cell-finbronectin adhesions in monocytes, while CD43-mediated cell adhesion was down-regulated. Interestingly, the enhancement of proliferation and IFN-$gamma$ production was striking observed in TmC-2-treated splenic lymphocytes. The activation seemed to be mediated by up-regulating intracellular signaling cascades such as PI3K/Akt and MAPK (ERK and p38) and by the involvement of surface receptors (dectin-1 and TLR-2). Therefore, our results suggest that this TmC-2 from T. matsutake can be developed as a promising immunostimulatory principle, applicable to people with lowered immunomodulatory potentials.