Human CD8 T cells exhibit similar phenotypic characteristics to mice after in vivo and in vitro antigen nonspecific stimulation. CD8 (purple) and CD25 (brown) expression in melanoma lesional biopsies after application of (A) vehicle or (B) 5% imiquimod cream daily for 14 days (40× magnification). (C) Dot plots depict gating schema and expression of HLA-DR and CD25 expression on human CD8⁺ T cells after 3 days of stimulation with PHA/IL-2 (TCR mimicking) or IL-2 alone in vitro. (D) Percentages of (TCR-dependent) CD25⁺HLA-DR⁺ (left) or PD-1⁺ (right) expressing CD45RO⁺CD8⁺ human T cells. (E) Percentage (left) and numbers (right) of CD25⁻HLA-DR⁺ (TCR-independently activated) human CD45RO⁺CD8⁺ T cells. (F) Percentages of CD25⁺ (left) and CD25⁻ (right) human CD45RO⁺CD8⁺ T cells after 14 days of indicated stimulation. Data are representative of at least 2 independent experiments (*P < .05, **P < .01, ***P < .001).