Biological and Pharmaceutical Bulletin
Online ISSN : 1347-5215
Print ISSN : 0918-6158
Effects of D-Fraction, a Polysaccharide from Grifola frondosa on Tumor Growth Involve Activation of NK Cells
Noriko KodamaKiyoshi KomutaNorio SakaiHiroaki Nanba
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Volume 25 (2002) Issue 12 Pages 1647-1650

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Natural killer (NK) cells are directly cytotoxic for tumor cells and play a primary role in regulating immune responses. We monitored levels of NK cell cytotoxic activity in cancer patients receiving D-Fraction extracted from maitake mushrooms (Grifola frondosa). Elevated levels of cytotoxic activity were maintained for one year. To elucidate the mechanisms underlying long-term activation of NK cells during treatment with D-Fraction, we examined tumor volume and levels of IFN-γ and TNF-α in MM46-bearing C3H/HeN mice to which D-Fraction was administered for 19 d. D-Fraction markedly suppressed tumor growth, corresponding with increases in TNF-α and IFN-γ released from spleen cells and a significant increase in TNF-α expressed in NK cells. This suggests that the D-Fraction activates NK cells even on the 20th day after treatment. Furthermore, D-Fraction increased macrophage-derived interleukin (IL)-12, which serves to activate NK cells. These results suggest that NK cells are not only responsible for the early effects of D-Fraction on tumor growth, but also for the long-term tumor-suppressive effects of D-Fraction through increased IL-12 released from macrophages.

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© 2002 The Pharmaceutical Society of Japan
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