Immunomodulatory activity and active mechanisms of a low molecular polysaccharide isolated from Lanzhou lily bulbs in RAW264.7 macrophages

•Lanzhou lily polysaccharides with low molecular weight were extracted from the bulbs by freeze-thaw method for the first time.•The polysaccharides structure was characterized by different physical and chemical experiments.•Cell proliferation, cytokines, and other experiments prove that polysaccharides have immunoactivation of RAW264.7.•RNA-seq and RNAi experiment revealed the immune regulation mechanism of the polysaccharides, it can activate the corresponding signaling pathways in the downstream of the G protein coupled receptor subunit.