Host-mediated antitumor effect of grifolan NMF-5N, a polysaccharide obtained from Grifola frondosa

 

Takeyama T, Suzuki I, Ohno N, Oikawa S, Sato K, Ohsawa M, Yadomae T

Tokyo College of Pharmacy, Japan.

The antitumor mechanism of grifolan NMF-5N, a beta-1,3-glucan obtained from mycelia of
Grifola frondosa, was examined. Grifolan NMF-5N did not show direct cytocidal effect on
cultured tumor cells. However, intraperitoneal injection of grifolan NMF-5N increased the
number of peritoneal exudate cells and peritoneal adherent cells which showed cytostatic activity
towards syngeneic tumor cells. In an in vivo assay, the administration of carrageenan, an inhibitor
of macrophage function, reduced the antitumor activity of grifolan NMF-5N. The delayed-type
hypersensitivity reaction was augmented in the grifolan NMF-5N-administered mice. The
administration of NMF-5N augmented the induction of cytotoxic T cells but the antitumor activity
of grifolan NMF-5N was reduced in athymic nu/nu mice. In addition, the treatment with anti-Thy
1,2 antibody and complement C' of spleen cells taken from mice which showed regression of
tumor due to grifolan NMF-5N, reduced the neutralizing effect in Winn assay. These results
suggested that grifolan NMF-5N shows antitumor activity via host-mediated mechanisms and
both macrophages and T cells play important roles in the mechanisms.

 

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