Fig. 3

CAR down-regulation is due to lysosomal degradation of CAR A, B, Surface CAR expression and cytotoxicity of CAR T cells that cocultured with U937^CD33 cells for 12 h in the presence of 20 mM NH₄Cl (A) or 1 µM latruculin A (B), at a 1:10 E:T ratio. Data shown are mean ± SEM of three experimental replicates. C, The percentage of CTV⁺, CAR⁺ cells in tumor cells cocultured with CD33 CAR T cells or tumor cells only and the CTV⁺, CAR⁺ cell percentage in CD33 CAR T cells after coculture with U937^CD33 or Nalm6^CD33 cells or CAR-T cells only for 4 h at a 1:15 E:T ratio. Data shown are mean ± SEM of three experimental replicates. D, The percentage of CTV⁺, CAR⁺ cells in tumor cells cocultured with CD33 CAR T cells or tumor cells only and the CTV⁺, CAR⁺ cell percentage in CD33 CAR T cells after coculture with U937^CD33 or Nalm6^CD33 cells or CAR-T cells only for 14 h at a 1:15 E:T ratio. Data shown are mean ± SEM of three experimental replicates. A–D, were representative data from at least three independent experiments. Assays were performed on day 10 after the initial T-cell culture. Unless otherwise noted, P values are determined by unpaired t-tests. The numbers on the graphs are P values