CD23.CAR⁺ and CD19.CAR⁺ T lymphocytes have equal cytotoxic activity against CD19⁺CD23⁺ tumor cells. (A) Expression of CD23 antigen on target cells used in the cytotoxicity assay. (B) Cytotoxic activity of CD19.CAR⁺ and CD23.CAR⁺ T lymphocytes obtained from healthy donors against CD23⁺ LCL targets. Cytotoxic activity was evaluated in a standard 4-hour ⁵¹Cr-release assay, and results are shown at E:T ratios of 40:1, 20:1, 10:1, and 5:1. Data represent the means ± SD of 7 different T-cell lines. **P ≤ .005 comparing NT and CAR⁺ T cells. The difference between the cytotoxic activity of CD19.CAR⁺ and CD23.CAR⁺ T lymphocytes was not statistically significant at any given E:T ratio. (C) Cytotoxic activity of CD23.CAR⁺ T lymphocytes generated from healthy donors against the wild-type Jeko-1 cell line or CD23⁺ cells. Cytotoxic activity was evaluated in a ⁵¹Cr-release assay, and results are shown at E:T ratios of 40:1, 20:1, 10:1, and 5:1. Data represent the means ± SD for 6 different T-cell lines. **P ≤ .005 comparing NT and CAR⁺ T cells. (D) Cytotoxic activity of CD23.CAR⁺ T lymphocytes generated from healthy donors against the wild-type BJAB cell line or CD23⁺ cells. Cytotoxic activity was evaluated in a ⁵¹Cr-release assay, and results are shown at E:T ratios of 40:1, 20:1, 10:1, and 5:1. Data represent the means ± SD for 6 different T-cell lines. **P ≤ .005 comparing NT and CAR⁺ T cells.