| Objectives:The changes and distribution of spleen and peripheral blood myeloid-derived suppressor cells (MDSCs) in tumor-bearing mice was studied, the corelation between peripheral blood MDSCs and serum nitric oxide was analysed, and its function in tumor progression and tumor escape was investigated.Methods:Orthotopic transplantation tumor model of hepatocarcinoma in mice was established. At the 7th,14th,21st day after tumor implantation, the propotion of MDSCs in spleen and peripheral blood was tested by Flow cytometry, their localization and semi-quantitative analysis was conducted by immunohistochemistry, serum nitric oxide was detected by the method of nitric acid reductase.Results:1. The propotion of spleen MDSCs in normal mice was (4.11±1.06)%. At the 7th,14th, 21st day after tumor implantation, the propotion of MDSCs was (6.07±1.82)%,(11.07±2.03)%,(16.49±3.18)%. The propotion of spleen MDSCs in tumor-bearing mice was significantly higher than normal mice (P<0.05). Accompany with tumor progression, the propotion of spleen MDSCs increased gradually. Under resting conditions, a few MDSCs were mainly localized in the red pulp of spleen. A dramatic increase in spleen MDSCs was oberseved in tumor-bearing mice and tightly accumulated in the marginal zones and periarteriolar lymphatic sheaths.2.The propotion of peripheral blood MDSCs in tumor-bearing mice was significantly higher than normal mice (P<0.05). At the 7th,14th,21st day after tumor implantation, the propotion of MDSCs was (8.65±1.01)%,(14.20±2.52)%,(27.51±2.98)%.3.The level of nitric oxide in normal mice was (57.03±16.94)μmol/L, which was significantly lower than in tumor-bearing mice(P<0.05). At the 7th,14th,21st day after tumor implantation, the level of nitric oxide in normal mice was (72.02±5.05)μmol/L,(94.70±3.34)μmol/L,(78.90±8.19)μmol/L.4.The level of nitric oxide positively correlated with the propotion of MDSCs by correlation analysis(r=0.869, P<0.01). Conclusions:1.The propotion of spleen MDSCs in tumor-bearing mice was significantly higher than normal mice. Accompany with tumor progression, the propotion of spleen MDSCs increased gradually. The propotion of spleen MDSCs is associated with tumor progression. MDSCs in tumor-bearing mice mainly localize at thymus-dependent area in spleen of mice. It shows that MDSCs can cause T suppression or dysfunction after interacting with T cell, promote tumor progression.2.The propotion of peripheral blood MDSCs in tumor-bearing mice was significantly higher than normal mice, indicating that the propotion of peripheral blood MDSCs in mice is associated with tumor progression. The level of serum nitric oxide in mice is associated with tumor progression. The propotion of peripheral blood MDSCs in tumor-bearing mice positively correlated with the level of serum nitric oxide. |
