Objective: To investigate the effect of autophagy on the survival and suppressive function of granulocytic myeloid derived suppressor cells (G-MDSCs) obtained from the spleen of Lewis lung carcinoma-bearing mice. Methods: Subcutaneous transplant tumor in mice was constructed with cultured Lewis lung carcinoma cells. G-MDSCs were obtained through MACS sorting method from the spleen of tumor-bearing mice, after CD11b and Ly-6G/Ly-6C tagged, the purity of cells was detected by flow cytometry. Cells Morphological characteristics of G-MDSCs were identified with optical microscope after stained with Wright-Giemsa stain. G-MDSCs were cultured within Rapamycin and chloroquine, and then collected to detect the level of autophagosomes formation marker—microtubuleassociated protein 1light chain 3-Ⅱ (LC3-Ⅱ) by Western blotting and flow cytometry. 7-amino-actinomycin D(7-ADD) staining was used to detect the effect of autophagy on the survival of G-MDSCs cultured with or without autophagy inhibitor 3-methyladenine (3-MA); the activity of arginase was measured with enzyme-linked immunosorbent assay(ELISA)in G-MDSCs. Results: G-MDSCs with high purity were obtained, and these cells have a typical polymorphonuclear morphology. The level of LC3-Ⅱ was up-regulated in G-MDSCs after treated with Rapamycin. Proportion of living cells and arginase activity were decreased in G-MDSCs with 3-MA treatment. Conclusion: Autophagy facilitates the survival and enhances the level of arginase in G-MDSCs in vitro. It may be implied that autophagy is involved in regulating the biological function of G-MDSCs.

［Key words］granulocytic myeloid derived suppressor cells; autophagy; Lewis lung carcinoma; 3methyladenine; arginase; immunotherapy