CD4 and head and neck squamous cell carcinoma: Compared to tumors which were classified as ‘Immunoscore high’ in immunohistochemical analyses, ‘Immunoscore low’ HNSCC tumors showed a significantly higher percentage of CD4+ T cells (67.0 ± 10.7% vs. 50.5 ± 5.9%; p < 0.05) and significantly lower percentages of CD8+ T cells (16.9 ± 12.8% vs. 37.3 ± 12.0%; p < 0.05; Figure 2C) in flow cytometry analyses.