Effect of Treatment with Interferon-γ and Concanavalin A on the Course of Infection of Mice with Salmonella typhimurium Strain LT-2

Abstract

Lymphokines have been shown to affect the resistance of mice to bacterial infections. To explore this effect further, mice were pretreated with 34 units per day for 5 days of a hybridoma supernatant containing primarily interferon-γ activity. Then, the mice were infected with one LD₅₀ of Salmonella typhimurium strain LT-2. The hybridoma supernatant fluid-treated mice were not protected; in fact, they died faster than did mice only infected with S typhimurium. When mice were pretreated under the same regimen with pure murine IFN-γ produced by recombinant DNA technology prior to infection, the mice were protected and 95% survived the infection. The hybridomas had been treated with concanavalin A (ConA) to induce IFN-γ. When mice were directly treated with ConA prior to infection with S. typhimurium, they also died more quickly than untreated controls. These data suggest that IFN-γ pretreatment can protect mice against infection with S. typhimurium, but that ConA pretreatment can counteract that effect.