Potent activity of short TSLPR CAR T cells is associated with a relative expansion of CD8⁺ CAR T cells in vivo. (A) Mice were injected with high-dose REH-TSLPR (5 × 10⁶) followed by late injection of short TSLPR CAR T cells (10 × 10⁶) on day 16. ACT, adoptive cell transfer. (B) Slightly increased relative number of CD4⁺ CAR T cells after CD3/CD28 bead-mediated expansion. This converts to a predominance CD8⁺/TSLPR CAR⁺ (measured by TSLPR Fc) at day 50 after injection. (C) Representative dot plots showing phenotype of short TSLPR CAR T cells before injection at day 20 after injection. (D) Relative percentages of naïve, central memory, and effector memory CAR T cells at day 20 after injection.