CD4 and peripheral arterial disease: A representative of activation markers CD69 and CD137 is shown in Figure 7A, and cumulative data for both activation markers and intracellular IFN-γ in CD69+ and CD137+, CD4+, and CD8+ T cells are shown in Figure 7B. CD8+CD69+ (p < 0.009) and CD4+CD137+ (<0.001) subsets were significantly increased in the PAD group as compared to the HC.