Abstract: Objective:To investigate the effects of low dose of dexamethasone on CD11b⁺ Gr-1⁺ myeloid-derived suppressor cells(MDSCs) in septic mice induced by lipopolysaccharide(LPS).Methods:The septic mice model was established by the intraperitoneal injection of LPS in BALB/c mice.The mice were randomly divided into the normal control group(NC group), sepsis group(SE group) and sepsis combined with dexamethasone group(SD group).The levels of serum interferon-γ and interleukin-10 were detected at 6, 12 and 24 hours.The percentage of CD11b⁺ Gr-1⁺ MDSCs in spleen and bone marrow of mice were detected at 12, 24, 48 and 72 hours.Results:Compared with the NC group, the levels of interferon-γ at 6 hours and interleukin-10 at 12 hours in SE group and SD group increased significantly(P<0.05 to P<0.01), and the difference of which between SE group and SD group was not statistically different (P<0.05).Compared with the NC group, the percentages of MDSCs in spleen at 12 to 72 hours in SE group and at 12 to 48 hours in SD group increased significantly (P<0.01), and the differences of the percentage of MDSCs at 24 to 72 hours between SE group and SD group were statistically different (P<0.05).Compared with the NC group, the percentages of MDSCs in bone marrow of SE and SD group increased significantly at 48 hours and 72 hours (P<0.05 to P<0.01).the differences of which at 48 and 72 hours between SE and SD groups were statistically significant(P<0.05 and P<0.01).Conclusions:Low dose of dexamethasone can inhibit the production and accumulation of MDSCs in septic mice induced by LPS.