Porcine interferon-gamma inhibits the growth of Legionella pneumophila in WiREF cells in vitro.

The intracellular growth of Legionella pneumophila in WiREF (Wistar rat embryonal fibroblast) cells was inhibited by porcine interferon-gamma. The effect was compared with that of different human interferons (alpha and gamma). The growth inhibition was dose-dependent and required the pretreatment of WiREF cells with interferon. The development of an antibacterial state of the cells was observed. When interferon was added together with bacteria or 1 d after the infection there was no inhibition. Also, there was no direct antibacterial effect of the interferon. In addition, cell pretreatment with a combination of interferon and antibiotics failed to show a synergistic effect.