FIG. 9.
Involvement of DC-derived IFN-γ in the induction of acquired resistance to a lethal L. monocytogenes infection. IFN-γ-deficient mice were infected intravenously with 5 × 104 CFU of L. monocytogenes, wild-type mice were infected intravenously with 5 × 105 CFU of L. monocytogenes, and DCs were purified from their spleens at 48 h after infection. Wild-type mice were immunized with 5 × 104 DCs from L. monocytogenes-infected, IFN-γ-deficient mice or DCs from L. monocytogenes-infected wild-type mice or uninfected, IFN-γ-deficient mice. Wild-type mice were injected with PBS only as a nonimmune control. They were challenged with 5 × 106 CFU of L. monocytogenes 4 weeks later. The numbers of bacteria in the spleens and livers of the mice were determined at 48 h after the challenge. Each result represents the mean ± the standard deviation for a group of four mice. An asterisk indicates a significant difference from the value for the nonimmune control group (P < 0.01). LMDC, L. monocytogenes-infected DCs.