Nitric oxide production and mycobacterial growth inhibition by murine alveolar macrophages: the sequence of rIFN-γ stimulation and Mycobacterium bovis BCG infection determines macrophage activation

Prestimulation with recombinant-interferon-γ (rIFN-γ) followed by Mycobacterium bovis BCG infection induced high nitric oxide production and potent mycobacterial growth inhibition in murine alveolar macrophages. Reversal of the sequence of treatments caused opposite effects, suggesting that a sequential 2-step process comprising first rIFN-γ stimulation and second mycobacterial infection is operative in the activation of alveolar macrophages.