Role of gamma interferon and tumor necrosis factor alpha in resistance to Salmonella typhimurium infection

Abstract

In mice infected with a sublethal dose of Salmonella typhimurium, the injection of an anti-gamma interferon (IFN-γ) monoclonal antibody increased bacterial proliferation in the spleen and led to death on day 7 or 8. Depletion of both CD4+ and CD8+ T cells with monoclonal antibodies in vivo had a much less marked effect during the first week of infection than the administration of anti-IFN-γ antibodies, suggesting that cells other than T lymphocytes participate in the production of IFN-γ at this time. Administration of anti-tumor necrosis factor alpha (TNF-α) antibodies to mice infected with a sublethal dose of S. typhimurium induced the same effect as anti-IFN-γ antibodies, while the administration of both antibodies resulted in a synergistic interaction. When mice were infected with an avirulent strain of S. typhimurium and challenged on day 7 either with a virulent strain of S. typhimurium or with Listeria monocytogenes, their resistance to reinfection was slightly depressed by anti-IFN-γ or anti-TNF- α antibodies given 1 day before challenge and much more strongly depressed by the simultaneous administration of both antibodies. Taken together, these results indicate that IFN-γ and TNF-α play an essential role in acquired resistance during the early phase of S. typhimurium infection.