Figure 6.

Repetitive stimulation with MC-38-CEA-A2Kb cells results in enriched HLA-A2–restricted, CEA₆₉₁-specific CTLs. C57BL/6-CEA-A2Kb mice (n = 4) were immunized three times at 2-week intervals with attenuated S. typhimurium harboring the pHI-691 vector. Mice were sacrificed 2 weeks after the last immunization, and isolated splenocytes were stimulated weekly with irradiated MC-38-CEA-A2Kb cells. After four stimulations, cells were harvested and cytotoxicity assays performed. (A) Expression of CD8 on stimulated cells. Stimulated splenocytes were stained with PE-conjugated isotype control antibody (thin dashed line) or anti-CD8 Ab (thick solid line). (B) Cytotoxicity assays performed with either unloaded or CEA₆₉₁-loaded B3 cells as targets.