Cytotoxicity of tk⁺ mH antigen-specific CTLs against leukemia and suicide induction by GCV administration in vitro. (A) The cytotoxicity of tk⁺ HA-1–specific CTLs (HA1-tk CTLs) generated from an HLA-A2^pos/HA-1^neg representative donor (HA1-tk #1) was evaluated against different HLA-A2^pos targets, including lymphoblastoid cell lines (LCL, □) and patient-derived leukemic cells typed for HA-1 (negative if R/R, positive if H/R or HH) and is expressed as the percentage of lysis at a 20:1 effector-to-target ratio. (B) The cytotoxicity of tk⁺ H-Y-specific CTLs (HY-tk CTLs) generated from an HLA-A2^pos/H-Y^neg representative (female) donor (HY-tk #1) was evaluated against different HLA-A2^pos targets, including lymphoblastoid cell lines (LCL, □) and leukemic cells derived from female (HY negative) or male (HY positive) patients and is expressed as the percentage of lysis at a 20:1 effector-to-target ratio. (C) Suicide induction on HA1 and HA1-tk CTLs at increasing concentrations of GCV (x-axis) is expressed as GCV sensitivity (y-axis, see “Functional characterization of human mH antigen-specific CTLs”). Results from the HA1-tk #1 donor are shown. (D) Suicide induction was also assayed on HY and HY-tk CTLs. Results from the donor HY-tk #1 donor are shown. (E) The cytotoxicity of HA1-specific CTLs generated either from PBLs (HA1 CTLs) or from tk⁺ T cells (HA1-tk CTLs) of the HA1-tk #1 donor is expressed as the percentage of lysis (y-axis) at different effector-to-target ratios (x-axis) against an HLA-A2^pos/HA1^neg lymphoblastoid cell line (HA1^neg LCL, ◊), an HLA-A2^pos/HA1^pos LCL (HA1^pos LCL, □), or ALL-CM leukemic cells (♦), which are HLA-A2^pos/HA-1^pos/H-Y^pos. (F) The cytotoxicity of CMV-specific CTLs (CMV CTLs) generated from PBLs of the HA1-tk #1 donor is expressed as the percentage of lysis (y-axis) at different effector-to-target ratios (x-axis) against ALL-CM leukemic cells loaded (♦) or not (◊) with the CMV peptide used for generation. (G) H-Y–specific CTLs were generated from PBLs (HY CTLs) and from tk⁺ T cells (HY-tk CTLs) of the HY-tk #1 donor and characterized for cytotoxicity against leukemia using appropriate reagents and control cell lines. (H) EBV-specific CTLs (EBV CTLs) were generated from PBLs of the HY-tk #1 donor and characterized.