Representative experiment of CTL-mediated cytotoxicity in vitro. T cells derived from the spleens of qVEGFR-immunized mice were tested against Flk-1–transfected CT26 target cells (A) and nontransfected CT26 (B) at different effector-target ratios by a standard 4-hour 51Cr release assay, as described in “Materials and methods.” T cells isolated from mice immunized with qVEGFR (•) did not show increased cytotoxicity against Flk-1–positive target cells (A) and Flk-1–negative target cells (B) compared with control groups, including mVEGFR (▪), ALUM (▴), or nonimmunized (⋄) mice. As a positive control, T cells from mouse vaccinated with the dendritic cells transfected with adenovirus encoding Flk-1 (○) showed increased cytotoxicity against Flk-1–positive target cells (A) but not against Flk-1–negative target cells (B). Error bars indicate SD.
