CAR-T cells are minimally impacted by PD-L1 expression on target cells. CD8+ and CD4+ CAR-T cells were co-incubated with CD19+ or CD19+/PDL1+ K562 target cells without exogenous cytokines and monitored for a % CARhi, b % Annexin V+, c % CD25+, d % Tim-3+, e % PD-1+, f CFSE intensity, and g target cell count. An asterisk indicates significant differences comparing co-incubations with CD19+ versus CD19+/PDL1+ K562 target cells at that time-point as determined by two-tailed unpaired Student’s t tests with the Bonferroni correction (p = 0.00019 in e and p = 0.00076 in g). Black arrows denote the addition of target cells to ensure sustained exposure to PD-L1. Average values of triplicates are shown with error bars indicating ± 1 s.d.