Fig. 6. Expression of activation markers on memory CD4⁺CTLA-4⁺ and memory DN CTLA-4^– T cells. PBMCs from HIV-infected and uninfected subjects were analysed for the surface expression of HLA-DR and the intracellular expression of Ki67 on gated CD3⁺ T-cell subsets ex vivo. (a) Expression of Ki67 (upper panels) and HLA-DR (lower panels) on memory CD4⁺ T-cells (CTLA-4^hi) and memory DN T cells (CTLA-4^–) from a representative treatment-naive HIV-infected subject and a representative HIV-negative control. (b) HLA-DR and Ki67 expression in these subsets (six subjects per group). (c) Expression of the activation marker Ki67 on the memory fraction of DN T cells (CTLA-4^–) from viraemic HIV-infected subjects (n = 17) compared with aviraemic cART-treated subjects (n = 15), elite controllers (EC, n = 15) and HIV-negative subjects (n = 15). Non-parametric Mann–Whitney two-tailed test P values are shown in (b) and (c). (d) Correlation between the expression of Ki67 on the memory fraction of DN T-cells (CTLA-4^–) and plasma viral load in HIV-infected treatment naive subjects (n = 17). Spearman correlation r (rho) and P values are indicated in (d).