FIG. 7.

PKO mice have numbers of LLO91-99-specific CD8⁺ T cells similar to those of WT mice but eliminate bacteria with delayed kinetics after challenge with L. monocytogenes. (A) WT (squares) and PKO (circles) mice were immunized with 1 × 10⁶ CFU of actA-deficient L. monocytogenes. The mice were challenged 28 days later with 1.5 × 10⁵ CFU of L. monocytogenes NPs (arrow). The number of CD8⁺ T cells specific for LLO91-99 was determined at each time point by intracellular cytokine staining for IFN-γ. Data are means ± SDs. (B) The numbers of CFU in spleen (open symbols) and liver (closed symbols) were determined on the indicated days after immunization. Dashed line, limit of detection. Data are from a representative experiment of three independent experiments and are the averages for three mice at each time point in each group.