We have already reported that the D-Fraction, a beta-glucan extracted from the fruiting body of the maitake mushroom (Grifola frondosa), activates cellular immunity and expresses anti-tumor effects. In this study we investigated the anti-tumor functions of D-Fraction in relation to its control of the balance between T lymphocyte subsets Th-1 and Th-2. D-Fraction decreased the activation of B cells and potentiated the activation of helper T cells, resulting in enhanced cellular immunity. It also induced the production of interferon (IFN)-gamma, interleukin (IL)-12 p70, and IL-18 by whole spleen cells and lymph node cells, but suppressed that of IL-4. These results suggest that D-Fraction establishes Th-1 dominance which induces cellular immunity in the population that was Th-2 dominant due to carcinoma.

The present study showed that oral mushroom beta-glucan treatment significantly increased IFN-γ mRNA expression but significantly reduced COX-2 mRNA expression within the lung. For LLC tumor model, oral Ganoderma lucidum or Antrodia camphorata polysaccharides treatments significantly reduced TGF-β production in serum. In addition, IL-12 and IFN-γ mRNA expression were significantly increased, but IL-6, IL-10, COX-2, and TGF-β mRNA expression were substantially following oral mushroom polysaccharides treatments. The study highlights the efficacious effect of mushroom polysaccharides for ameliorating the immune suppression in the tumor microenvironment. Increased M1 phenotype of tumor-associated macrophages and attenuated M2 phenotype of tumor-associated macrophages could be achieved by ingesting mushroom polysaccharides.