Expression of the innate resistance gene Ity in mouse Kupffer cells infected with Salmonella typhimurium in vitro.

Early innate resistance to salmonellae in mice is controlled by the chromosome 1 gene Ity which regulates the in vivo net growth rate of bacteria in the RES by an unknown mechanism. It similarly controls innate resistance to Leishmania donovani, BCG and Mycobacterium lepraemurium. Murine Kupffer cell cultures were infected with virulent Salmonella typhimurium and followed for 12 h. Multiresistant organisms were used so that the antibiotics in the medium could not interfere with the results; extracellular bacteria were removed by repeated washes. Monolayers from resistant Ityr (C3H/He, CBA, A/J) and Ityr/s (B10 x A/J)F1 mice resisted infection with S. typhimurium C5 better than those from susceptible Itys (DBA/1, BALB/c, B10.M) mice, which were progressively lost from the culture plates at a faster rate than resistant monolayers. Organisms were clearly visible inside large vacuoles in the macrophages. The results confirm and amplify results of others on salmonella-infected peritoneal and splenic macrophages, and support the view that the Ity gene is expressed as a function of macrophages.