Effect of treatment of mice with sera containing gamma interferon on the course of infection with Salmonella typhimurium strain LT-2.

Swiss/Webster mice pre-treated with gamma interferon preparations and then infected with Salmonella typhimurium showed significantly increased survival when compared to mock interferon-treated or control mice. Nude mice similarly pre-treated with gamma interferon showed similar increased survival after S. typhimurium infections. If gamma interferon treatment were delayed until the commencement of the S. typhimurium infection, no effect on mortality was observed. The increased survival of the gamma interferon-treated mice did not appear to be due to increased antibody production, more rapid clearing of bacteria from the circulation, or enhanced uptake of bacteria by phagocytic cells of the spleen, liver, or lungs. The number of viable bacteria isolated from the spleens and livers of interferon-treated mice was significantly lower over time than in organs of mock interferon-treated or untreated mice, suggesting the gamma interferon treatment may have resulted in more efficient killing of bacteria by phagocytic cells.