Figure 5.
The DNA minigene vaccine pHI-691 induces HLA-A2–restricted killing of MC-38-CEA-A2Kb cells. (A) Surface expression of HLA-A2 and CEA by MC-38-CEA-A2Kb (left) and MC-38-CEA (right). Tumor cells were washed and incubated with isotype control Ab (thin dashed lines), anti–HLA-A2 (thin solid lines), or anti-CEA (heavy solid lines) and stained with PE-conjugated (Fab′)2 of goat anti–mouse Ig Ab. Groups of C57BL/6-CEA-A2Kb mice (n = 4) were immunized three times at 2-week intervals with attenuated S. typhimurium harboring the vectors indicated. Mice were sacrificed 2 weeks after the last immunization, and isolated splenocytes were stimulated with irradiated MC-38-CEA-A2Kb cells for 5 days. Thereafter, cytotoxicity assays were performed with (B) MC-38-CEA-A2Kb or (C) MC-38-CEA as target cells. max, maximum.