Antileukemic activity of CAR.CD19-transduced PB-derived CTLs. (A) Specific lysis of allogeneic CD19⁺ (Raji cell line and primary B-ALL cells) and the CD19⁻ HDLM-2 cell line by PB-derived CAR.CD19⁺ MV-CTLs compared with nontransduced controls at E/T ratio of 40:1. Relative contribution of NK-cell activity was measured using K562 targets. Means and SDs from 3 experiments are shown (*P < .05; **P < .01). (B) IFNγ production by CAR.CD19⁺CD3⁺ MV-CTLs (left plot), upon coculture with CD19⁺ targets compared with unstimulated CAR.CD19⁺ CTLs (top right plot) and nontransduced CTLs (bottom right plot) stimulated with CD19⁺ targets as measured by intracellular flow cytometry. Sample plots from donor 3 shown. (C) Relative expansion of CD19⁺ primary B-ALL cells from an HLA-matched bone marrow transplant recipient cocultured with nontransduced MV-CTL (left plot) or CAR.CD19⁺ CTLs (right plot). (D) Pattern of cytokine release from coculture experiment after 24-hour incubation as measured by CBA in 2 donors. Transduced CTLs plus B-ALL; nontransduced CTLs plus B-ALL (***P = .04). No significant release of cytokines was observed by nonstimulated nontransduced and transduced CTLs (not shown). TD CTLs indicates transduced cytotoxic T lymphocytes; NT CTLs, nontransduced cytotoxic T lymphocytes.