CD4 and head and neck squamous cell carcinoma: Overall, HPV+ HNSCC exhibits several features associated with a more inflamed or “hotter” immune microenvironment such as increased B cell infiltrates and higher frequencies of PD-1+ CD8+ TILs, T helper type 1 (TH1) CD4+ T cells, TH17 CD4+ T cells, and T follicular helper (TFH) CD4+ T cells (Figure 1).