Figure 7. PD-L1 inhibits CAR T cell effector function.

(A) 3T3 fibroblasts were transduced to either express MSLN alone (MSLN⁺, left) or coexpress MSLN in addition to PD-L1 (MSLN⁺ PD-L1⁺, right). (B–D) M28z and MBBz CAR T cell effector functions were assessed after stimulation with 3T3 MSLN⁺ or MSLN⁺ PD-L1⁺ targets. PD-L1 inhibits M28z and MBBz CAR T cell accumulation upon repeated antigen stimulation (B), cytolytic function following 2 stimulations with MSLN⁺ PD-L1⁺ tumor cells (C), and Th1 effector cytokine secretion upon the first stimulation (D). Data represent the mean ± SEM of 3 replicates or are plotted as individual points and are representative of at least 2 independent experiments.