Breach of IL-12 monopoly in the initiation of type 1 immunity to intracellular infections: IL-12 is not required.

IL-12 is believed to play an important role in type 1 T-cell differentiation and type 1 cytokine IFN-gamma release by T- and NK-cells and macrophages in host defense against intracellular infections by bacteria, parasites, fungi and viruses. However, recent studies by us and others have provided unequivocal evidence that while IL- 12 is critically required for the development of type 1 immunity to the majority of intracellular bacterial, …