IL-12 was more up-regulated in response to PVM in BALB/c than in C57BL/6 mice.
IL-12p40-/- and wild-type neonatal and adult BALB/c mice were challenged with PVM.
IL-12p40-/- mice showed less weight loss than wild-type mice after PVM challenge.
The percentage of regulatory T cells was higher in the lungs of IL-12p40-/- mice.
IL-12p40-/- mice showed greatly decreased allergic sensitization after PVM infection.