Expression of Programmed Death-Ligand 1 in Laryngeal Carcinoma and its Effects on Immune Cell Subgroup Infiltration

To study the expression of programmed death-ligand 1 (PD-L1), and its effects on CD8⁺ tumor infiltrating lymphocytes (TILs) and tumor associated macrophages (TAMs) in human laryngeal squamous cell carcinoma. Sixty-nine patients with laryngeal carcinoma and 10 with vocal cord leukoplakia received tumor resection at Neck Surgery Department in the Second Affiliation Hospital of Jilin University (Changchun, Jilin) from Jan. 2010 to Dec. 2015. The expressions of PD-L1, CD8, CD16 and CD206 in laryngeal carcinoma, paracancerous and vocal cord leukoplakia tissues were detected with immunohistochemistry. The associations between PD-L1 expression and clinicopathologic features, expression of TAMs and CD8⁺ T cell infiltration were analyzed. Expression of PD-L1 is significantly higher in laryngeal carcinoma than in paracancerous or leukoplakia tissue. The expression of PD-L1 is closely associated with stage of laryngeal cancer, histological differentiation and neck lymphatic metastasis. PD-L1 expression is negatively correlated with the number of CD8⁺ TILs and CD16⁺ cells (M1 type TAMs), while is positively associated with CD206⁺ (M2 type TAMs). PD-L1 is highly expressed in the laryngeal cancer with the tumor microenvironment immunosuppression.