Figure 4.

Bystander killing induced by P4-redirected T cells. (a) Mesothelin immunostaining showing regional diversity of mesothelin expression in high-grade papillary serous ovarian adenocarcinoma. Original magnification was ×200. (b) Heatmap illustration of mesothelin expression level in primary and metastatic ovarian carcinoma cases. (c) P4-z CAR T cells were cocultured with antigen-negative Cr⁵¹-labeled AE17 (upper) or C30 tumor cells (lower) in the presence or absence of unlabelled antigen-positive AE17M (upper) or A1847 cells (lower), respectively, for 4 hours (left panels) and 18 hours (right panels) at the indicated effector to target ratio. As positive controls, P4-z CAR T cells were cocultured with antigen-positive Cr⁵¹-labeled AE17M (upper) or A1847 tumor cells (lower) in the presence or absence of unlabelled antigen-negative AE17 (upper) or C30 cancer cells (lower), respectively. Percent specific target cell lysis was calculated as (experimental − spontaneous release) ÷ (maximal − spontaneous release) × 100. Error bars indicate standard deviation. CAR, chimeric antigen receptor; E/T ratio, effector cell to target cell ratio.