Abstract: Objective: To separate Grifola frondosa fruit body polysaccharide by ethanol precipitation and ultrofiltrationr (UF) and investigate the effects of Grifola frondosa fruit body polysaccharides on immune function of mice. Methods: Water-soluble polysaccharides were extracted from Grifola frondosa fruit body with hot water and then the residue was further extracted with dilute sodium hydroxid to obtain alkali-soluble polysaccharides. Both the two polysaccharides were precipitated out from the extracting solutions by ethanol, and they were further separated by UF according to their molecular weights (> 1000 kD, 100 to 1000 kD and 10 to 100 kD) respectively. The immunocompetences of different polysaccharide components derived from Grifola frondosa were investigated using immunocyte cultivation technique in vitro. Results: The yield of water-soluble polysaccharides is 6.67%, and the yield of alkali-soluble polysaccharides is 5.88%. The yields of water-soluble polysaccharides with molecular weight more than 1000 kD (GFP100) , 100 to 1000 kD (GFP10) and 10 to 100 kD (GFP1) are 3.99%,0.51% and 3.94%, respectively, and the yields of alkali-soluble polysaccharides with molecular weight more than 1000 kD ( GFAP100), 100 to 1000 kD (GFAP10) and 10 to 100 kD (GFAP1) are 2.42%, 2.32% and 3.04%, respectively. All the polysaccharide components separated by UF can significantly increase the proliferation rate of mouse spleen lymphocytes. Conclusion: The ultrafiltration separation of Grifola frondosa polysaccharides is simple and feasible.

Key words: Grifola frondosa polysaccharides, ultrafiltration, molecular weight, immunocompetence