Characteristics Of Tumor Infiltrating Lymphocytes In Adenocarcinoma And Squamous Lung Cancer

ObjectThis study aims to examine the subtypes of tumor infiltrating lymphocytes (TILs), and characterize the inhibitory receptors including TIGIT and PD-1 expression in TILs of adenocarcinoma (LAC) and squamous lung cancer (SCC).MethodsSamples of lung cancer and adjacent lung tissue come from patients who took lung resection from Jul 2015 to Nov 2015 in the Second Affiliated Hospital of Zhejiang University. LAC and SCC patients with paired information (including sex, age, tumor stage, smoking) were enrolled for analyzing in current study. We analyzed TEL subsets and TIGIT and PD-1 expression in T cells by flow cytometry and immunohistochemistry. We also tested the T cell proliferation after blocking TIGIT and PD-1 receptors.ResultsCD8+T lymphocytes represent the dominant population of tumor infiltrating lymphocytes in lung squamous cell carcinoma relative to lung adenocarcinoma. TIGIT is upregulated and co-expressed with PD-1 on tumor infiltrating lymphocytes in NSCLC, especially in lung squamous cell carcinomaTumor infiltrating lymphocytes highly expressed TIGIT and PD-1 exhibit enhanced proliferation after TIGIT and PD-1 blocked.ConclusionDespite of general information (including sex, age, tumor stage, smoking history) which could influence the results, CD8+T lymphocytes represent the dominant population of tumor infiltrating lymphocytes in lung squamous cell carcinoma relative to lung adenocarcinoma. Immune checkpoints TIGIT and PD-1 expressed in T cells more highly in SCC patients. Those may explain why checkpoint inhibitors nivolumab and pembrolizumab show more effective in SCC patients. As immune checkpoints TIGIT and PD-1 are coexpressed in T cells of LAC and SCC patients, maybe immune checkpoint inhibitors could be combined to treat lung cancers.