CD8A and head and neck squamous cell carcinoma: Elevated interleukin 23 (IL-23) and IL-6 levels released by HNSCC cells may promote T helper 17 (Th17) cell proliferation (Kesselring et al., 2010), while Th17 and Tregs proliferation is associated with the functional impairment of infiltrating CD8+ T cells in HNSCC (Kesselring et al., 2010; Liu et al., 2018b).