Efficient tumor cell lysis by CD8-LV TCR-transduced T cells. Activated PBMCs (A-B) or purified CD8⁺ T cells (C) were transduced with CD8-LV or VSV-G-LV at the indicated MOIs, and expanded in 100 IU/mL IL-2–containing medium. On day 12, transduced cells were transferred into 10 IU/mL IL-2–containing medium for 2 to 3 days, and TCR-T58 expression was determined by HLA-A2-Tyr multimer staining (data not shown). Identical numbers of CD8⁺/TCR-T58⁺ cells were applied as effector cells and used to normalize E:T ratios. (A) TCR-T58-modified PBMCs were incubated with Mel-624.38 cells or as controls with Mel-A375 or SK-Mel-28 cells at the indicated E:T ratios for 4 hours, and target cell killing was quantified using a FACS-based cytotoxicity assay. Mean values ± SEM calculated from 3 independent experiments are shown. The difference between CD8-LV-TCR-T58 and VSV-G-LV-TCR-T58 (MOI = 2) treated groups is highly significant (P < .0001). (B) TCR-T58–expressing PBMCs transduced by the indicated vectors at the indicated MOIs were incubated with Mel-624.38 cells for 4 hours. Mean values ± SEM calculated from 2 independent experiments are shown. The difference between CD8-LV-TCR-T58 and VSV-G-LV-TCR-T58 (MOI = 100) treated groups is significant (P < .0001), whereas the difference between VSV-G-LV-TCR-T58 (MOI = 2) and VSV-G-LV-TCR-T58 (MOI = 100) treated group is not (P > .05). (C) Purified CD8⁺ T cells transduced by the indicated vectors were incubated with Mel-624.38 cells for 4 hours, and specific target-cell lysis was determined. Representative results from 1 of 2 independent experiments with T cells from 2 different donors are shown. The difference between CD8-LV-TCR-T58 and VSV-G-LV-TCR-T58 (MOI = 2) treated groups is significant (P < .001).