In vitro treatment of HEp-2 cells with human tumor necrosis factor-alpha and human interferons reduces invasiveness of Salmonella typhimurium.

Enteroinvasive bacteria, like Salmonella typhimurium, can be internalized in in vitro cultured epithelioidal cells, like HEp-2 cells. This phenomenon is inhibited by pretreatment of cells with human tumor necrosis factor alpha (TNF-alpha) in a dose- and time-dependent manner. The effect was also reproduced in other cell types, including diploid embryo fibroblast cells. The TNF-alpha effect was neutralized by anti-TNF-alpha antibodies. No synergistic effect was produced by combinations of TNF-alpha with either interferon alpha or gamma. Unlike the effects of interferons, TNF-alpha inhibited the invasiveness of Shigella flexneri and the TNF-alpha effect was not inhibited by cycloheximide.