Abstract: Background and purpose: T cell immunoglobulin and mucin-domain-containing molecules 3 (Tim-3) plays a pivotal role in immune regulation. It participates in the occurrence and development of a variety of diseases, and Tim-3 is associated with immune escape and poor prognosis. The aim of this study was to investigate the expression of negative costimulatory molecule, Tim-3, in macrophages in non-small cell lung cancer (NSCLC) and explore the clinical significance of the expression. Methods: A total of 126 human lung cancer tissue specimens were obtained from pathologically confirmed and newly diagnosed NSCLC patients. The expression level of Tim-3 was analyzed by immunohistochemistry staining. Correlation analysis was performed to study the relationship between Tim-3 expression in macrophages and clinicopathological features. Survival analysis was performed by Kaplan-Meier. Results: Tim-3 was mainly expressed in the cytoplasm and cell membrane of macrophages. Tumor size, lymph node metastasis, TNM stage were significantly correlated with Tim-3 expression level (P=0.002, 0.045 and 0.022, respectively). Tim-3 expression in macrophages was negatively correlated with the prognosis of patients. Higher Tim-3 expression had a shorter overall survival (OS) in patients with stage Ⅲ NSCLC (χ²=12.910, P=0.000; Median OS: 80 months vs 32 months). Moreover, the expression level of Tim-3 had negative correlation with disease-free survival (DFS) in patients with stage Ⅲ NSCLC (χ²=6.135, P=0.013; Median DFS: 41 months vs 24 months). In addition, Tim-3 expression in lymphocytes was negatively correlated with OS and DFS in patients with stage Ⅲ NSCLC (χ²=4.737, P=0.030, Median OS: 80 months vs 47 months; χ²=5.882, P=0.015, Median DFS: 41 months vs 24 months). Conclusion: Tim-3, as a key negative regulator in anti-tumor immunity, contributes to the tumor immune evasion. It has an adverse influence on the prognosis of NSCLC patients.

Key words: T cell immunoglobulin and mucin-domain-containing molecules 3, Non-small cell lung carcinoma, Macrophages, Prognosis