Expression of PD-1 on CD 8 + T cells from the peripheral blood of patients with esophageal squamous cell carcinoma and its clinical implications

Background: Esophageal cancer is one of the most common gastrointestinal tumors worldwide with poor prognosis and its prognostic evaluation is still an urgent problem. Materials and Methods: Our study was performed to determine the expression of programmed death-1 (PD-1) on CD8+ T cells from the peripheral blood of patients with esophageal squamous cell carcinoma (ESCC) and to discuss its biological and clinical significance. T-lymphocyte subpopulations in the peripheral blood and PD-1 expression on the surface of CD8+ T lymphocytes from 60 patients with ESCC (ESCC group) and 25 healthy controls (control group) were counted and analyzed. Results: The results revealed that the percentages of CD3+ T and CD4+ T cells, as well as the CD4+/CD8+ T cells ratio, were significantly lower in the ESCC group than that in the control group, whereas the difference in CD8+ T cells between the ESCC group and the control group did not reach statistical significance. The positive rates of PD-1 expressed in CD8+ T cells from the ESCC group’s peripheral blood were remarkably higher than those from the control group, which was related to tumor cell differentiation and lymph node status but not to sex, age or tumor location. Patients with high PD-1 expression have significantly lower rates of both progression free survival (PFS) and overall survival (OS) compared with those of the low PD-1 expression group; high PD-1 expression was also an independent prognostic factor in patients with ESCC. Conclusion: These findings suggest that T-lymphocyte subpopulations in the peripheral blood of patients with ESCC conferred immunosuppression to varying degrees. PD-1 expression level on the surface of CD8+ T cells provides a prognostic value of ESCC patients.