Effect of myeloid-derived suppressor cells reduced by anti-Gr-1 antibody on CD8 + T cell number and tumor growth / 肿瘤研究与临床

ABSTRACT

Objective:To explore the effects of reducing myeloid-derived suppressor cells (MDSC) of Lewis lung cancer mice by anti-Gr-1 antibody on tumor growth and CD8 + T cell number in peripheral blood, spleen and tumor tissues. Methods:A mouse Lewis lung cancer cells tumor-bearing mouse model was constructed. MDSC were reduced by intraperitoneal injection of anti-Gr-1 antibody every 48 h (observation group), and model mice injected with equal amount of 0.7% NaCl solution were used as control group, and the injections lasted for 3 weeks. Three mice were killed on days 7, 14 and 21 after tumor inoculation. Flow cytometry was applied to dynamically monitor the proportions of MDSC and CD8 + T cells in the peripheral blood, spleen and tumor tissues of mice at different time points. Seven days after tumor inoculation, the longest and shortes diameters of subcutaneous tumors in mice were measured at regular intervals to monitor the tumor size of both groups. Results:The tumor volume in both groups increased with the extension of time, and the increase trend in the observation group was relatively slow. On day 20, the tumor volume in the observation group was smaller than that in the model group [(1 978±315) mm 3 vs. (1 356±432) mm 3, P = 0.001]. On days 7, 14 and 21 after tumor inoculation, the proportions of MDSC and CD8 + T cells in the peripheral blood, spleen and tumor tissues of mice of the observation group were lower than those of the control group. The proportion of MDSC in the peripheral blood of mice of both groups showed an upward trend over time, with the observation group showing a slower upward trend than the control group. The proportion of CD8 + T cells in the peripheral blood of both groups showed an upward trend from day 7 to day 14, and the observation group showed a more significant upward trend. The proportion of CD8 + T cells in both groups showed a downward trend from day 14 to day 21. The changes in the proportions of MDSC and CD8 + T cells in the spleen of mice of both groups were similar to those in the peripheral blood, but the proportion of CD8 + T cells in the control group showed a more significant upward trend than the observation group from day 7 to day 14. The proportion of MDSC cells in the tumor tissues of the control group showed a significant upward trend from day 7 to day 14, and stabilized from day 14 to day 21. The proportion of MDSC cells in the observation group slowly increased from day 7 to day 14, and decreased from day 14 to day 21. The proportion of CD8 + T cells in both groups showed an upward trend from day 7 to day 14, and decreased from day 14 to day 21. Conclusions:Anti-Gr-1 antibody can effectively reduce MDSC in the peripheral blood, spleen and tumor tissues of Lewis lung cancer tumor-bearing mice, and inhibit tumor growth, but also reduce the level of CD8 + T cells in the peripheral blood, spleen and tumor tissues.