Expression of CD4+ and CD8+ Tumor-Infiltrating Lymphocytes in Oral Squamous Cell Carcinoma and Their Relationship With Clinicopathological Parameters: A Cross-Sectional Study.

Background Oral squamous cell carcinoma (OSCC) is the most common malignant neoplasm of the oral cavity. The tumor microenvironment (TME) is a dynamic ecosystem composed of components contributed by both the tumor and the host. The immune cells of TME, mainly CD4+ and CD8+ tumor-infiltrating lymphocytes (TILs), suppress the proliferation of cancer cells and play a crucial role in the progression of OSCC. The present study aims to analyze the immunohistochemical expression of CD4+ and CD8+ TILs in OSCC and to compare and correlate them with clinicopathological parameters. Methodology A total of 75 formalin-fixed paraffin-embedded samples of cases diagnosed with primary OSCC were immunostained with CD4+ and CD8+ antibodies and their expression was compared with the clinicopathological parameters. Results There was a significant positive correlation between CD4+ and CD8+ expression (r = 0.655, p = 0.001). Both CD4+ (r = -2.37, p = 0.041) and CD8+ (r = -0.348, p = 0.002) expressions negatively correlated with the TNM stage (r = -2.37, p = 0.041) of OSCC. CD8+ expression positively correlated with histopathological grade (r = 0.288, p = 0.012). Conclusions The study findings suggest that CD4+ cells are essential to maintain and sustain CD8+ TIL-mediated anti-tumor response. CD4+ and CD8+ TILs are key players in cell-mediated adaptive immunity and prevent tumor progression and metastasis. Strikingly, the higher grade of tumors despite heavy CD8+ infiltration may possibly be due to cancer immunoediting.