Figure 2.

ζ, CD28-ζ, and CD28-ζ–OX40 CAR redirected CIK cells efficiently kill tumor cells in vitro. Cytokine-induced killer (CIK) cells were engineered with the ζ, CD28-ζ, and CD28-ζ–OX40 CAR, and cocultivated (1.25 − 10 × 10³ CAR⁺ cells/well) with CEA⁺ LS174T or CEA⁻ Colo320 tumor cells (each 2 × 10⁴ cells/well) for 48 hours. Cytolysis was determined by an XTT-based colorimetric assay and supernatants were analyzed for interferon- (IFN-γ) by enzyme-linked immunosorbent assay. Side-by-side comparison of (a) ζ and CD28-ζ CAR engineered CIK cells and (b) CD28-ζ and CD28-ζ–OX40 engineered CIK cells. Numbers represent mean values of triplicates ± SD. A representative assay is shown. Statistical analyses were performed using Student's t-test. *P < 0.05. CAR, chimeric antigen receptor; CEA, carcinoembryonic antigen.