Abstract: Objective: To determine the effects of Grifola frondosa polysaccharide, lentinan, Ganoderma lucidum polysaccharide, Lycium barbarum polysaccharide and yeast glucan on the morphology, proliferation, cytotoxicity and IFN-γ secretion of human NK cells. Methods: Pure human NK cells, prepared by PBMC based ex vivo expansion, were treated with each polysaccharide at concentrations of 100 mg/L and 50 mg/L, respectively. The proliferation, cytotoxicity and IFN-γ secretion of NK cells were tested after 72 h treatments. Results: No significant changes in the proliferation of NK cells were observed between polysaccharide treatment groups and control group. However, increased cytotoxicity of NK cells could be observed for four polysaccharide treatment groups and some changes in cell morphology were also detected. The cytotoxicity of NK cells increased by 5.89% and 9.1% (P＜0.05) after treatment with 100 mg/L and 50 mg/L of Ganoderma lucidum polysaccharide, and increased by 5.7% and 6.9% (P＜0.05) after treatment with 50 mg/L of Grifola frondosa polysaccharide and Lycium barbarum polysaccharide, respectively. In addition, the IFN-γ secretion of NK cells increased by 255 pg/mL and 202 pg/mL (P＜0.05) separately after treatment with 50 mg/L of Grifola frondosa polysaccharide and lentinan. Conclusion: Grifola frondosa polysaccharide, Ganoderma lucidum polysaccharide and Lycium barbarum polysaccharide enhances the cytotoxicity of NK cells, but not by promoting its proliferation. Grifola frondosa polysaccharide and lentinan promote the IFN-γ secretion to a certain extent in vitro and thus have immunoregulatory effects on NK cells.

Key words: human NK cells, polysaccharide, cytotoxicity, IFN-γ