Relationship between the expressions of PD-L1 and tumor-infiltrating lymphocytes in oral squamous cell carcinoma

• Published in: Oral oncology Vol. 47; no. 12; pp. 1148 - 1153
• Main Authors: Cho, Young-Ah, Yoon, Hye-Jung, Lee, Jae-Il, Hong, Sam-Pyo, Hong, Seong-Doo
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.12.2011; Elsevier
• Subjects: Apoptosis; B7-H1 Antigen - metabolism; Biological and medical sciences; Cancer immunity; Carcinoma, Squamous Cell - metabolism; CD4-Positive T-Lymphocytes - metabolism; CD8+ lymphocytes; CD8-Positive T-Lymphocytes - metabolism; Female; Fibroblasts - metabolism; Hematology, Oncology and Palliative Medicine; Humans; Lymphocytes, Tumor-Infiltrating - metabolism; Male; Medical sciences; Middle Aged; Mouth Neoplasms - metabolism; Oral squamous cell carcinoma; Otolaryngology; Otorhinolaryngology. Stomatology; PD-L1; Prognosis; Tumor-associated fibroblasts; Tumor-infiltrating lymphocytes; Tumors; Upper respiratory tract, upper alimentary tract, paranasal sinuses, salivary glands: diseases, semeiology; PD-L1; Oral squamous cell carcinoma; Tumor-infiltrating lymphocytes; Cancer immunity; Tumor-associated fibroblasts; CD8 + lymphocytes; CD8+ lymphocytes; lymphocytes; Stomatology; ENT; Malignant tumor; Immunity; Cancerology; CD8; Oral cavity disease; Fibroblast; Lymphocyte; Cancer
• DOI: 10.1016/j.oraloncology.2011.08.007
• ISSN: 1368-8375

Summary Tumor-infiltrating lymphocytes (TILs) are considered to represent immune reactions of the host to a malignant tumor. Programmed death receptor ligand-1 (PD-L1) is a surface protein that blocks the function of T lymphocytes and is expressed on cancer cells. Tumor-associated fibroblasts (TAFs), which influence tumor growth have also been reported to express PD-L1 and thus inhibit TILs. In the present study, we investigated the densities of CD4+ /CD8+ TILs, PD-L1 expression of tumor cells and TAFs in oral squamous cell carcinoma (OSCC). Forty-five cases of OSCC were selected. We evaluated PD-L1 expression and the infiltration degree of each lymphocyte by immunohistochemical examination. These data were analyzed in connection with clinicopathological factors. Peritumoral CD8+ TILs were observed in every patient with OSCC, and their densities were correlated with lymph node metastasis ( P < 0.001), tumor size ( P = 0.003), and clinical stage ( P < 0.001). PD-L1 expression on OSCC cells was observed in 39 cases and was associated with the lower density of intratumoral CD8+ TILs ( P = 0.047). PD-L1 expression of tumors <4 cm in size was correlated with the histological grade of the tumor ( P = 0.022). TAFs were positive for PD-L1 in 18 cases. Peritumoral TILs were significantly associated with tumor size, lymph node metastasis and clinical stage. Though PD-L1 expressed by OSCC cells did not affect patients’ survival, its correlation with decreased number of intratumoral TILs suggests that the development of a strategy to block the interactions of PD-L1 with TIL would be a useful tool for inhibiting tumor growth.