Induction of T-bet expression correlates with the transition to a granzyme B⁺perforin^hi phenotype. (A) PBMCs from HLA A1 and HLA A2 donors were labeled with CFSE and then cultured with and without VTE or NLV for 5 days in the presence of IL-2, IL-12, or no cytokine. T-bet and Eomes expression in antigen-specific T cells was assessed as outlined in “Methods.” Data represent the mean fluorescence intensity of T-bet (left panel) or Eomes (right panel) expression in antigen-specific T cells stimulated with cognate peptide (blue) or incubated for 5 days without stimulation (red). (B) VTE- and NLV-specific T cells stimulated for 5 days with cognate peptide with and without cytokine were assessed for the expression of granzyme B and perforin. Data represent the proportion of granzyme B⁺ and perforin^hi VTE and NLV-specific T cells, following in vitro culture with and without peptide.