CD40 and tuberculosis: While our own data show that CD40-/- DCs and CD40LT-treated DCs infected with Mtb do not affect IFN-γ responses in a closed system in vitro (Figs 1 and 3), treatment of Mtb-infected DCs with CD40LT does augment IFN-γ responses in the lungs 6 days after intratracheal instillation of DCs (Figs 5 and 6), suggesting that engaging the CD40-CD40L pathway enhances both Th1 and Th17 responses in vivo and may lead to a more balanced Th1/Th17 immunity to TB.