Cytotoxic reactivity of the FSP26-specific T cell bulk culture toward tumor cell targets. (A) Specific lytic activity against T2 cells loaded with FSP26, derived from the Caspase-5(-1) frameshift mutation, as compared to cells presenting the control peptide P68. (B) HLA-A0201-restricted killing of LoVo-A2 (HLA-A0201-transfected LoVo cells) endogenously expressing the Caspase-5(-1) FSP is compared to the HLA-A0201-negative parental cell line. (C) Specific lysis of the Caspase-5(-1)-expressing, HLA-A0201+ Colo60H cell line is shown in contrast to that of the Caspase-5(wt)-expressing, HLA-A0201+ control cell lines SW707 and SW480. The lack of reactivity against the NK sensitive cell line K562 excludes NK cell activity. (D) Killing efficiency against the HCT116 colon carcinoma cell line [HLA-A0201+, Caspase-5(-1)] in the presence or absence of IFN-gamma (200 U/ml, overnight). Target cells were labeled with ⁵¹Cr-sodium chromate for 1 h. Different effector-to-target cell ratios (E:T ratios) are shown. All results are displayed as the mean and standard deviation from three replicate wells.