The polysaccharide isolated from Pleurotus nebrodensis （PN-S） shows immune-stimulating activity in RAW264.7 macrophages

A novel Pleurotus nebrodens＆ polysacchafide （PN-S） was purified andcharacterized, and its immune-stimulating activity was evaluated in RAW264.7 macrophages. PN-S induced the proliferation of RAW264.7 cells in a dose-dependent manner, as determined by the MTT assay. After exposure to PN-S, the phagocytosis of the macrophages was significantly improved, with remarkable changes in morphology being observed. Flow cytometric analysis demonstrated that PN-S promoted RAW264.7 cells to progress through S and G2/M phases. PN-S treatment enhanced the productions of interleukin-6 （IL-6）, nitric oxide （NO）, interferon gamma （INF-7）, and tumor necrosis factor-α （TNF-α） in the macrophages, with up-regulation of mRNA expressions of interleukin-6 （IL-6）, inducible nitric oxide synthase （iNOS）, interferon gamma（INF-γ） and tumor necrosis factor-α （TNF-α） being observed in a dose-dependent manner, as measured by qRT-PCR. In conclusion, these results suggest that the purified PN-S can improve immunity by activating macrophages.