IFNG and infection: To investigate whether APC populations from the three different compartments may differ in their capability to activate the natural T cells that were spontaneously activated during the course of infection, we compared the CD11c+ cell populations from the BAL, lung parenchyma and the spleen for their ability to re-activate mycobacterial antigen-specific, IFN-γ-releasing type 1 T cells that naturally developed in vivo during mycobacterial infection.