Differential expression of the effector molecules perforin and granzymes A, B, and K in CMV-specific T cells correlates with the intensity of T-bet expression. (A) PBMCs from CMV-seropositive donors were stained with CMV-specific pMHC multimers and anti-CD8 and then assessed for the intracellular expression of perforin and granzymes A, B, and K. (A) Histograms represent the analysis of perforin and granzyme A, B, and K expression in ELR/K and IPS-specific T-cell populations in a single donor. (B) Data represent the mean ± SEM of the proportion of perforin^hi, granzyme A⁺, granzyme B⁺, or granzyme K⁺ epitope-specific T cells. (C) Data represent the correlation between the T-bet mean fluorescent intensity in CMV-specific T cells and the proportion of perforin^hi, granzyme A⁺, granzyme B⁺, or granzyme K⁺ T cells.