Immunomodulatory effect of a polysaccharide fraction on RAW 264.7 macrophages extracted from the wild Lactarius deliciosus.

The mushroom polysaccharides are important substances with variety of functions, especially to the human body's immunomodulation effects. In this work, a polysaccharide fraction (LDP-1) was extracted and purified from the fruiting bodies of a rare wild Lactarius deliciosus. LDP-1 with molecular weight of 9.8 × 105 Da showed an obvious immunological activity to the RAW 264.7 cells. It had no significant suppressive but promotive effects on proliferation of the macrophages. The production of nitric oxide (NO) presented a concentration-dependent manner after treated with the LDP-1, and the maximum yield of NO was 39.15 μM. LDP-1 could promote the phagocytic uptake ability of the RAW 264.7 cells significantly, and many of the antennas produced around the cells correspondingly. The cytokines of TNF-α, IL-1β and IL-6 were secreted increasingly in a concentration-dependent manner, which were 4.83, 17.8 and 11 times than that of the control, respectively. Western blotting analysis confirmed that NF-κB levels in the nucleus were increased while cytoplasmic inhibitor of NF-κB (IκB-α) degraded after treated with the LDP-1, indicating the RAW 264.7 cells probably be stimulated by LDP-1 through activating the IκB-α-NF-κB pathway. These results demonstrated that LDP-1 could be used as a kind of immunomodulatory agent for healthcare potentially.