Peptide-restricted cytotoxic activity of FSP26-specific CTL clone 1. The FSP26 specificity of CTL clone 1 was tested in the presence of unlabeled cold targets, T2 cells pulsed either with peptide FSP26 (solid rhombus) or with control peptide P68 (open rhombus) at an inhibitor-to-target cell ratio of 30:1. Lysis of HCT116 cells without cold targets is shown as a control (open triangles). Killing of target cells is depicted at different effector-to-target cell ratios (E:T ratios). All results are displayed as the mean and standard deviation from three replicate wells.