This study investigates the relevance of tumor-infiltrating lymphocytes (TILs) in oral squamous cell carcinoma (OSCC). Immunohistochemical analysis of stromal/tumoral CD4+, CD8+ and FOXP3+ TILs is performed in 125 OSCC patients. Potential relationships with the expression of tumoral PD-L1 and cancer stem cell (CSC) markers (NANOG, SOX2, OCT4, Nestin and Podoplanin (PDPN)) are assessed. CD4+ and CD8+ TILs are significantly associated with smoking and alcohol habits. CD4+ and CD8+ TILs show an inverse relationship with NANOG and SOX2 expression, and FOXP3+ TILs is significantly correlated with Nestin and PDPN expression. High infiltration of CD4+ and CD8+ TILs and a high tumoral CD8+/FOXP3+ ratio are significantly associated with tumors harboring positive PD-L1 expression. Infiltration of stromal/tumoral FOXP3+ TILs and a low stromal CD8+/FOXP3+ ratio are significantly associated with better disease-specific survival. Multivariate analysis reveals that the stromal CD8+/FOXP3+ TILs ratio is a significant independent prognostic factor. Regarding OSCC patient survival, the CD8+/FOXP3+ TILs ratio is an independent prognostic factor. TILs may act as biomarkers and potential therapeutic targets for OSCC.
Keywords: CD4; CD8; FOXP3; Nestin; OCT4; Podoplanin; TILs; oral cancer.