Cytotoxic potential of immunization-induced T cells ex vivo and after IVS. (A) Cytotoxic activity ex vivo (red dashed line) and after IVS (blue solid line) for 3 patients including patient 6 (P6) who demonstrated perforin expression ex vivo (Figure 3A). Cytotoxicity is portrayed at different effector-to-target ratios and as specific killing (relevant versus irrelevant lysis of target cells). In no case was irrelevant killing above 5%. In the bottom panels, cytotoxicity by a 209-2M specific (red dashed line) and a Tax-specific (blue line) clone is shown for comparison. (B) Uptake of GFP/HLA-peptide complexes is shown for 3 patients with melanoma (P3, P1, P6) and one HAM patient (P11); for each patient the left scatter plot shows the uptake when an irrelevant peptide (gag peptide) is used for stimulation. On the right the uptake is shown when 209-2M or Tax, respectively, is used for pulsing of GFP/HLA complex-transduced HmyA2GFP cells. (C) Differential expression of genes associated with T-cell activation between antigen-specific CD8⁺ T cells from 3 patients with melanoma (209-2M-specific) ex vivo or after IVS and patients with HAM (Tax-specific). Shown genes are those that were significantly differentially expressed (unpaired, two-tailed Student t test; P₂ < .05) between the immunization-induced (209-2M–specific) CD8⁺ T cells ex vivo in 3 patients with melanoma and the Tax-specific CD8⁺ T cells in 3 patients infected with HTLV-1. Only immune-relevant genes are shown.