[The number of myeloid-derived suppressor cells in the peripheral blood and tumor tissues in patients with gastric cancer and its clinical significance].

To investigate the number of myeloid-derived suppressor cells (MDSCs) in peripheral blood, tumor tissue and para-tumor normal tissues in patients with gastric cancer in an attempt to explore the relationship between MDSCs expression and clinicopathologic characteristics. Peripheral blood was collected from 62 gastric cancer patients and 20 healthy volunteers (HC group). Gastric cancer tissues and adjacent normal tissues were obtained from 12 of the 62 gastric cancer patients. HLA-DR^- CD33⁺ CD11b⁺ MDSCs were analyzed by flow cytometry. Student's t-test, One-way ANOVA and Mann-Whitney U test were used to explore the correlation between MDSCs expression in peripheral blood and the depth of tumor invasion, degree of differentiation, TNM stage and lymph node metastasis. Compare with the HC group, the number of MDSCs in peripheral blood of newly-diagnosed gastric cancer patients was higher (P<0.01). The number of MDSCs in peripheral blood of gastric cancer patients was significantly associated with the depth of invasion, degree of differentiation, TNM stage and lymph node metastasis (P<0.05). The expression of MDSCs from gastric cancer tissues was obviously higher than that of the adjacent tissues in the same patient. The number of MDSCs in peripheral blood from recurrent/metastasis group was obviously higher than that from non-recurrent/metastasis group (P<0.05). In addition, compare with the HC group, the expression of negative costimulatory molecule T-cell immunoglobulin- and mucin-domain-containing molecule 3 (Tim-3) on HLA-DR^- CD33⁺ CD11b⁺ MDSCs in peripheral blood was higher in patients with gastric cancer. MDSCs expression in peripheral blood of gastric cancer patients was closely associated with tumor malignant degree and tumor recurrence/metastasis.