CD8A and head and neck squamous cell carcinoma: The frequencies of CD4+ and CD8+ T cells were determined in the lymphocyte gate in patients with HNSCC and the percentages of different cytokine-producing subsets of CD4+ and CD8+ T lymphocytes including IFN-γ+, TNF-α+, IL-4+, IL-17+, IL-10+ and TGF-β+ T cells were assessed (Figs. 1, 2 and Table 1, unstimulated cells served as controls; see Additional file 1: Figures S1 and S2).