Granulocyte-Macrophage Colony-Stimulating Factor (GM-CSF) Regulates Cytokine Induction by 1,3- β -D-Glucan SCG in DBA/2 Mice In Vitro

Sparassis crispa Fr. is an edible/medicinal mushroom that recently became cultivable in Japan. SCG is a major 6-branched 1,3-β-D-glucan in S. crispa showing antitumor activity. We recently found that the splenocytes from naive DBA/1 and DBA/2 mice strongly react with SCG to produce interferon-γ (IFN-γ). In this study, cytokines induced by SCG were screened and found to be IFN-γ, tumor necrosis factor-α (TNF-α), granulocyte-macrophage colony-stimulating factor (GM-CSF), and interleukin-12(IL-12p70). The addition of recombinant murine GM-CSF (rMuGM-CSF) to spleen cell cultures from various strains of mice synergistically enhanced IFN-γ, TNF-α and IL-12p70 in the presence of SCG. In contrast, neutralizing GM-CSF using anti-GM-CSF monoclonal antibody(mAb) significantly inhibited IFN-γ, TNF-α, and IL-12p70 elicited by SCG. We conclude that GM-CSF is a key molecule for cytokine induction by β-glucan, and GM-CSF induction by SCG is the specific step in DBA/2 mice in vitro.