HIV-specific PD-1⁺CD8⁺ T cells from TP patients are less able to proliferate than their counterparts in LTNPs. (A) Comparison of proliferation profiles of total CD8⁺ T cells from representative LTNPs and TPs. CFSE-labeled PBMCs were harvested at different time points, and CD8⁺ T-cell proliferation was analyzed using flow cytometry. (B) Proliferation profiles for PD-1⁺CD8⁺ and PD-1⁻CD8⁺ T cells in a representative TP patient. Cells were gated on PD-1⁺ (top) and PD-1⁻CD8⁺ T cells (bottom) at different incubation times. (C) PD-1/PD-L1 blockade restores expansion of CD8⁺ T cells from TP patients in the presence of either anti–PD-L1 antibodies (bottom) or the corresponding isotype control antibodies (top). (D) Summary data for the frequency of CFSE^lowCD8⁺ T cells from LTNPs (n = 5) and TPs (n = 7) that were incubated in vitro in the presence of anti–PD-L1 antibodies or isotype control antibodies for different incubation times. P values were shown for the differences of CFSE^lowCD8⁺ T-cell percentages between TP patients and LTNPs. Error bars indicate standard deviation. (E) Representative expansion of pentamer⁺CD8⁺ T cells in the presence of anti–PD-L1 antibody in TP patients (n = 4). Values in the upper right quadrant represent the percentage of pentamer⁺CD8⁺ T cells.