SALMONELLA-TYPHIMURIUM INFECTIONS IN MICE DEFICIENT IN INTERLEUKIN-4 PRODUCTION - ROLE OF IL-4 IN INFECTION-ASSOCIATED PATHOLOGY

Mice harboring mutations in the IL-4 gene (IL-4(-/-)) were infected wi th a range of Salmonella typhimurium HWSH derivatives using different routes of infection, Compared with IL-4(+/+) mice, IL-4(-/-) mice exhi bited a delayed time to death following infection with wild-type S. ty phimurium HWSH. Groups of IL-4(+/+) mice infected with S. typhimurium HWSH purE, a less virulent derivative, showed sporadic deaths and harb oured micro- or macroabscesses in their tissues, particularly associat ed with the liver. However, IL-4(-/-) mice infected with similar doses of S. typhimurium HWSH purE bacteria were resistant to killing and fa iled to develop detectable abscesses, Abscess formation in IL-4(-/-) m ice could be induced by i.v. administration of rIL-4 during the S. typ himurium HWSH purE infection. The immune response in both IL-4(-/-) an d IL-4(+/+) mice was of the Th1-type, Viable salmonella bacteria could be found associated with abscesses. Both IL-4(-/-) and IL-4(+/+) mice were resistant to killing by S. typhimurium aroA.