Characterization of the EpCAM peptide-specific CTL responses against HepG2 CSCs.

(A) IFN-γ release by antigen-specific CTLs stimulated by antigens. Naïve T cells stimulated by co-culturing with tumor antigen-pulsed DCs were analyzed by ELISA for their production of IFN-γ. (B and C) Results from a cytotoxicity assay of CD8⁺ T cells activated by tumor antigen-pulsed DCs. Different DCs were co-cultured at a ratio of 1:5 with lymphocytes for 5 days. The non-adherent cells were collected and counted as effector cells. The effector cells were co-cultured with the EpCAM positive (B) and EpCAM negative (C) HepG2 cells at different ratios for 6 h at 37°C in a 5% CO₂ incubator. The data are expressed as the mean±SD, and significant differences between the treated groups were detected using ANOVA followed by the Dunnett’s test. ^# p<0.05 compared with the DCs or DC-CTLs, and * p<0.05 compared with the TL-CTLs.