CD4 and rheumatoid arthritis: Unlike CD27−CD28− CD4+ T cells, the frequencies of TNF‐α+, IFN‐γ+, CD107a+, and polyfunctional TNF‐α+IFN‐γ+CD107a+ cells within the CD27−CD28− CD8+ T cell compartments were not significantly diminished in RA patients (Figure 6F).