The Expression And Clinical Significance Of CD8~+CD39~+T Cells In Human Gastric All Colorectal Carcinoma

Objective:CD39(ENTPD1)is an extracellular nucleotide hydrolase expressed by cell membrane.As a rate-limiting enzyme,CD39 plays a key role in the process of hydrolysis of extracellular ditriphosphate nucleotides into an immunosuppressive adenosine.Studies have shown that CD39 disorders are closely related to a variety of human cancer diseases,and play a role in inhibiting immune cell activity and promoting tumor immune escape.In this study,we describe the expression of a CD8+T cell subgroup characterized by surface expression of CD39 in the tissues and peripheral blood of patients with gastric cancer(GC)and colorectal cancer(CRC).To investigate the phenotypic characteristics and cellular functions of these cells and their role in the genesis and development of tumors.Methods:Clinical specimens of GC and CRC patients admitted to the general surgery department of the first affiliated hospital of Soochow university from March 2019 to September 2019 were collected,including preoperative peripheral blood of the patients and fresh tumor tissue and corresponding para-cancer tissue specimens after surgery,as well as peripheral blood of healthy volunteers as control.Peripheral blood mononuclear cells were isolated by gradient density centrifugation.Tissue samples were prepared with tissue cell suspension by enzymatic digestion.Then flow cytometry was used to analyze the proportion and distribution of CD8+CD39+T cells in peripheral blood and tissues after treatment.In order to further clarify the phenotypic characteristics of CD8+CD39+T cells,flow cytometry was used to analyze the expression of PD-1 and Tim-3 on the membrane surface of CD8+CD39+T cells and CD8+CD39-T cells.Intracellular flow staining was used to detect IFN-? and TNF-? secretion of CD8+CD39+T cells and CD8+CD39-T cells in tumor tissues.Results:The proportion of CD8+CD39+T cells in peripheral blood of patients with GC and CRC was higher than that of healthy volunteers(P<0.05).The proportion of CD8+CD39+T cells in GC tissues was significantly higher than that in paracancer tissues(P<0.01),and the proportion of CD8+CD39+T cells in CRC tissues was also higher than that in paracancer tissues(P<0.05).PD-1 and Tim-3 were expressed to varying degrees on the surface of CD8+CD39+T cells in peripheral blood and tumor tissues of patients with GC and CRC.Compared with CD8+CD39+T cells,PD-1 and Tim-3 were highly expressed in CD8+CD39+T cells in peripheral blood of patients with GC(P<0.05).Similarly,CD8+CD39+T cells in peripheral blood of CRC had higher expression of PD-1 and Tim-3 than CD8+CD39-T cells(P<0.05).Compared with CD8+CD39+T cells,CD8+CD39-T cells in GC had higher expression of PD-1 and Tim-3(P<0.01).Similarly,CD8+CD39+T cells in CRC tissues had higher expression of PD-1 and Tim-3 than CD8+CD39+T cells(P<0.05).Intracellular cytokine detection found that CD8+CD39+T cells had low secretion of IFN-y and TNF-? in tumor tissues of patients with GC and CRC compared with CD8+CD39-T cells.The secretion of IFN-y in CD8+CD39+T cells in GC and CRC patients was lower than that in CD8+CD39-T cell group,but the difference was not statistically significant(P>0.05).The secretion of TNF-? in CD8+CD39+T cells in GC was significantly lower than that in CD8+CD39-T cells(P<0.01).The secretion of TNF-? in CD8+CD39+T cells in CRC tumor tissues was lower than that in the CD8+CD39+--T cell group,with statistically significant differences(P<0.05).Conclusion:In patients with GC and CRC,the proportion of CD8+CD39+T cells in peripheral blood and tumor tissues increased,and CD8+CD39+T cells were more likely to accumulate in tumor tissues.CD8+CD39+T cells in peripheral blood and tumor tissues of GC and CRC have higher expression of PD-1 and Tim-3 than CD8+CD39-T cells,showing the phenotypic characteristics of depletion.However,compared with CD8+CD39+T cells,CD8+CD39-T cells in GC and CRC tumor tissues secreted a low level of TNF-?,showing impaired cytokine secretion.The results suggested that in patients with GC and CRC,CD8+T cells with high expression of CD39 were depleted of T cells,which weakened the immune response to the tumor,inhibited the anti-tumor immune response of the body,and promoted the proliferation and invasion of the tumor.