Orally administered interferon-gamma but not tumor necrosis factor-alpha suppress infection with Salmonella typhimurium in a mouse model.

Intragastrically inoculated Salmonella typhimurium produces a systemic infection in mice with high mortality. We have examined the effect of interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha on the development of the disease. IFN-gamma reduced penetration of bacteria into the gut epithelial cells, reduced the development of bacteremia, reduced mortality and prolonged the length of survival of mice both after peroral and after intraperitoneal administration. On the other hand TNF-alpha had a similar effect only when given intraperitoneally but not by peroral route. These findings indicate that the mechanisms by which these two cytokines influence the development of S. typhimurium infection are different. This is the first observation that perorally administered cytokines may have local and systemic effects on bacterial infection.