Figure 5. Aging and replicative senescence markers in human T lymphocytes. PBMCs from healthy young (< 28 y) and old (> 56 y) donors were stained for CD28 and CD57 and run on LSR II flow cytometer. (A) Autophagy levels (Mean BDS) in CD8⁺ T cells from young (< 28 y, n = 8) and old (> 56 y, n = 8) donors under basal and basal+I (for 2 h) conditions (mean ± SEM, *p < 0.0499 between young and old basal+I). (B) Representative dot plots from a young and an old donor showing percentages of CD28 and CD57 cells gated on CD8⁺ T cells. (C) Bar graph showing % of CD8⁺ lymphocytes with CD28 and CD57 markers in four young and old donors (mean ± SEM, p = 0.0571 for CD8 CD28 population and *p = 0.0286 for CD8 CD57 population). (D) Overlaid histogram of γH2AX (DNA double-strand break) levels of CD8⁺ lymphocytes from three young and old donors gated on CD28⁺CD57^- population (geometric mean ± SEM, *p = 0.0286). (E) Overlaid histogram of FAS (CD95) levels of CD8⁺ lymphocytes from four young and old donors gated on CD28⁺CD57^- population (geometric mean ± SEM, *p = 0.0286). PBMCs from four healthy young and old donors were cultured under control and starved conditions for 2 h and stained for CD8, CD57, LC3 and Lyso-ID. (F) Colocalization of LC3 and lysosomal marker in CD8⁺CD57^+/− cells, expressed as mean BDS ratio between starved and basal treatments (mean ± SEM, n = 5 (young donors), n = 8 (old donors), **p = 0.0049, *p = 0.035).