In vivo persistence and antileukemia efficacy of mH antigen-specific tk⁺ CTLs in NOD/scid mice. (A) At different time points (x-axis) after ALL-CM leukemia inoculum and later infusion of unmodified CMV-specific CTLs (CMV CTLs, ■), unmodified (HA1 CTLs, ◊), or tk⁺ HA-1–specific CTLs generated from the HA1-tk #1 donor, cytotoxic T lymphocyte chimerism (y-axis, see “In vivo evaluation of the antileukemia efficacy of human mH antigen-specific CTLs”) was evaluated in the peripheral blood of individual NOD/scid mice by flow cytometry. Control mice were infused with PBS (□). Means ± SD of the data from n = 5 mice/group and results from an unpaired Mann-Whitney U test statistical analysis are shown (**P < .01 for cytotoxic T lymphocyte chimerism at day 3). (B) At days 3 and 7 after infusion, the percentage of circulating tk⁺ HA-1–specific CTLs expressing IL-7Rα (y-axis) was evaluated by flow cytometry. (C) At different time points (x-axis), mice were also individually monitored for ALL-CM chimerism (y-axis). Mean log percentages of circulating leukemic cells from n = 5 mice/group ± SD (y-axis) are shown (***P < .005). (D-F) Cytotoxic T lymphocyte chimerism, IL-7Rα expression, and ALL-CM chimerism were also monitored in mice inoculated with leukemia and later infused with unmodified EBV-specific CTLs (EBV CTLs, ■), unmodified (HY CTLs, ◊), or tk⁺ HY-specific CTLs generated from the HY-tk #1 donor (*P < .05 for cytotoxic T lymphocyte chimerism at day 3; **P < .01; ***P < .005).