CD8A and infection: Using an in vitro T cell priming system, Moretto et al. showed that only DC that were proficient to produce IL-12 in response to Ec were able to stimulate and expand Ag-specific naïve CD8+ T cells to become IFNγ producers and this result was consistent with the incapacity of IL-12-defficient mice to generate CD8+ T cells that express IFNγ and cytotoxic activity in vivo and that protect mice from lethal infection (Moretto et al., 2010).