Inhibition of tumor growth by β-glucans through promoting CD4 T cell immunomodulation and neutrophil-killing in mice.

β-glucans are polysaccharides comprising β-D-glucoses with various bioactivities. Herein, we extracted three β-glucans from Lentinus edodes with different sources and assessed their antitumor activities on a mice model with intragastric, intraperitoneal and intratumoral injection. Three polysaccharides were shown to have the same chemical structure of β-(1,3)-glucan with β-(1,6) branches, and exhibited S-180 tumor-suppressing ability with good safety. It was found that β-glucans up-regulated CD4 T cell level in lymphoid organs decreased by tumor-burden, indicating promotion of immunomodulation. β-glucans targeted tumors in vivo even after oral or intraperitoneal injection. Furthermore, β-glucans not only targeted to lymphoid organs and increased CD4 T cells number, but also enhanced CD4 T cells and neutrophils populations in tumors. It was proposed that β-glucans promoted CD4 T cell immunomodulation and neutrophils infiltration into tumors, leading to tumor growth inhibition. These findings reveal that β-glucans can be used as an effective agent for cancer immunotherapy.