Role of interleukin-23-dependent antifungal immune responses in dendritic cell-vaccinated mice.

CD40 ligand (CD40L) transduction of antigen-pulsed dendritic cells (DCs) can result in antigen-specific humoral immune responses even in CD4(+) T-cell-depleted settings. Here, we show that CD40L transduction of DCs results in the induction of interleukin-12p40 (IL-12p40), IL-12p70, and IL-23. Using DCs that were deficient in IL-12p40, IL-12p35, or IL-23p19, we show that these molecules are dispensable for primary IgG1 responses to Pneumocystis, but IgG2c was dependent on IL-12p40 and IL-23p19 but not IL-12p35. Antigen-specific recall responses in CD4-deficient mice were critically dependent on IL-12p40 and IL-23p19 expression in DCs and were not affected by the lack of IL-12p35. To confirm that this defect in recall was due to IL-23, transduction of IL-12p40(-/-) DCs with a recombinant adenovirus expressing functional IL-23 restored recall responses in DC-vaccinated CD4-deficient mice. These data show that DC-produced IL-23 is critical for vaccine-induced antigen-specific IgG2c and recall antibody responses in the setting of CD4(+) T-cell depletion.