Effects of interferon and tumour necrosis factor on development of intracellular bacterial infections

Invasiveness of the epithelial cells in the gut by Salmonella, Shigella, enteroinvasive Escherichia coli and other facultatively intracellular enteropathogenic bacteria, is an important pathogenetic factor in the course of infection. This process is inhibited when cells are pretreated with different types of interferons as demonstrated in animal and in culture models. The tumour necrosis factor seems to have minor effect on this process. Mostly the internalization process is reduced, and, to a lesser degree, there is a decrease in adhesiveness to the cell surface. The internalization process is dependent on active cell metabolism. Interferon effect was not expressed when the cultures were treated with protein synthesis inhibitors. Shiga toxin inhibited the anti-invasive effect of interferons in toxin-susceptible cells.