Figure 8. Lm autolysins provide essential inflammatory signals that promote long-term protective memory CD8⁺ T cells.

(A) Experimental design for (B-E). (B) Kinetics of Lm-specific LLO_91–99/K^d+ (tet⁺) CD8⁺ T cells in the blood of WT BALB/C mice immunized with indicated Lm. (C) Phenotypic and functional characterization of LLO-specific tet⁺ splenic memory CD8⁺ T cells 35 d post immunization with 0.1×LD₅₀ WT, ΔSecA2, Δp60ΔNamA and SU Δp60ΔNamA Lm. In (B, C), blood or spleens were harvested and cells either stained for cell-surface CD8, tet, CD62L, KLRG1 or restimulated ex vivo for 4–6 hrs with the LLO_91–99 epitope and stained for intracellular granzyme B, IFN-γ and CCL3 and surface CD8. (D) Titers of viable WT Lm CFU in the spleen and liver of mice immunized with indicated Lm with or without CpG nucleotides, and challenged with WT Lm for 48 hrs. (E) Frequencies of LLO-tet⁺ CD8⁺ T cells and expression of KLRG1 in the blood 8 and 21 d after immunization with indicated Lm. Data shown are the pool of 2–4 replicate experiments, each symbol featuring an individual mouse and p-values are indicated. Data plots (B) or histogram bars (C-E) average mean values+/− SEM or mean with each symbol representing an individual mouse.