CD28 and head and neck squamous cell carcinoma: We found predictive value for prognosis in these T cell subsets when we divided the HNSCC patients based on cutoffs for the median frequency of either CD8+CD28+ (> or <47.50%), CD8+CD28- T lymphocytes (> or <52.5%) or CD8+CD28−CD127−CD39+ Treg (> or <13.5%); specifically, patients with CD8+CD28+ T cell values lower than the cutoff, or CD8+CD28− T cells and CD8+CD28−CD127−CD39+ Treg values greater than the cut-off, had remarkably reduced survival (Figure 1D–F).