Augmentation of telomere length and telomerase activity of HIV-1–specific CD8⁺ T cells after antibody-mediated PD-L1 blockade. (A) Dot plots reflecting proliferative activity of HIV-1–specific CD8⁺ T cells in the presence or absence of PD-L1–blocking antibodies. CFSE^dim proliferating HIV-1–specific CD8⁺ T cells after antigenic stimulation and bulk CFSE^bright CD8⁺ T cells were sorted according to the gates indicated. Numbers in quadrants reflect proportion of gated lymphocytes. (B) Telomere length of HIV-1–specific CD8⁺ T cells proliferating in the presence or absence of PD-L1–blocking antibodies as well as of the corresponding nonproliferating bulk CD8⁺ T cells. (C,D) Telomerase activity of bulk CD8⁺ T cells and sorted HIV-1–specific CD8⁺ T cells that were stimulated with antigenic peptides in the presence or absence of PD-L1–blocking antibodies, as determined by RQ-TRAP with subsequent analysis by gel electrophoresis (panel C; vertical lines have been inserted to indicate repositioned gel lanes) and after normalization to a reference cell line as described in “Methods” (D). Horizontal bars in panels B and D reflect means.