Effect of Sasa veitchii extract on immunostimulating activity of β-glucan (SCG) from culinary-medicinal mushroom Sparassis crispa Wulf.:Fr. (higher Basidiomycetes).

Fungal β-glucan is a representative pathogen-associated microbial pattern (PAMP) from mushroom, yeast, and fungi, and stimulates innate as well as acquired immune systems. It is a widely used functional food to enhance immunity. Such plant extracts have been known as folk medicines and reported to show various biological activities beneficial to human health, such as anti-tumor, anti-allergic, and anti-inflammatory activities. In the present study, the cooperative effect of bamboo water-soluble methanol precipitation (BWMP), a macromolecular fraction of the hot-water extract of Sasa veitchii (Japanese folk medicine Kumazasa), and the β-glucan from the medicinal mushroom Sparassis crispa (SCG) was analyzed in vitro using DBA/2 mice. The splenocytes from male DBA/2 mice were cultured with BWMP in the presence of SCG, and the responses were assessed by measuring cytokines. BWMP suppressed IFN-γ and GM-CSF production by SCG, but not TNF-α production. To analyze the specificity of the reaction, similar experiments were conducted with BWMP in the presence of bacterial lipopolysaccharide (LPS); however, none of the cytokines were inhibited. Cytokine production of splenocytes by SCG was suggested to be largely dependent on the binding of lymphocytes with dendritic cells. Functions of BWMP were also analyzed by mixed lymphocyte reaction, and IFN-γ production was suppressed. These findings suggested that BWMP modulated the cell-to-cell contact induced by SCG and inhibited cytokine production. It is strongly suggested that the plant extracts modulate the immunostimulating effects of medicinal mushrooms. Cooperative effects of plants and mushrooms would be an important issue for functional foods.