摘要Background:Altered immunoresponse is associated with tumorigenesis and cancer progression.This study assessed the levels of tumor-infiltrating CD3+ or CD8+ T lymphocytes and interleukin-2 (IL-2) protein in radically resected non-small cell lung cancer (NSCLC) tissues to predict overall survival (OS) of the patients.Methods:Paraffin-embedded tissue specimens from 129 NSCLC patients were retrospectively collected for immunostaining of CD8+,CD3+,and IL-2 expression.Clinicopathological and survival data were collected and analyzed using the Chi-squared test,Kaplan-Meier curves,and the log-rank test or the Cox regression model.Results:The data showed a significant inverse association between CD8+ T lymphocyte levels and IL-2 expression (r =-0.927; P =0.000) and between the levels ofCD8+ and CD3+ T lymphocytes (r =-0.722; P =0.000),but a positive association between CD3+ T lymphocyte levels and IL-2 expression (r =0.781; P =0.000) in NSCLC tissues.Furthermore,the levels ofCD3+ and CD8+ T lymphocytes and IL-2 expression were associated with tumor stage (P =0.023,0.006,and 0.031,respectively) and the level ofCD8+ T lymphocytes was associated with the patient gender (P =0.024).In addition,the levels ofCD8+ T lymphocytes were associated with an unfavorable 5-year OS,whereas patients with high levels ofCD3+ T lymphocytes in tumor lesions and IL-2-expressing tumors had significantly better 5-year OS rates than patients with low levels.Conclusions:The levels ofCD8+ T cells in tumor lesions and IL-2 expression were both independent predictors of OS for these NSCLC patients.Thus,the detection of tumor-infiltrating CD3+ or CD8+ T lymphocytes and IL-2 expression could be useful to predict the prognosis of radically resected NSCLC patients.