Antibiotic treatment following heterologous boost recapitulates dependence on CD40L for mCD8+ T cell expansion.

<p>Mice were immunized with 10⁶ pfu VV-OVA and boosted 21 days later with 5×10⁶ cfu Lm-QV in the presence of MR1 or control antibody treatment. 8 hours following boost, indicated groups were treated with ampicillin to accelerate bacterial clearance. OVA_257–264-specific memory CD8+ T cell responses were assessed 5 days post-boost using intracellular cytokine staining for IFN-γ (<i>n</i> = 5). (A) Representative intracellular cytokine staining (median shown, ±SEM). (B) Total OVA_257–264-specific (IFN-γ+) CD8+ T cells (mean, ±SEM). *, P<0.05, Mann-Whitney. (C) Serum cytokines 24 h post-boost in untreated versus ampicillin-treated animals (mean, ±SEM). Data are representative of three independent experiments.