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 with a range of Salmonella typhimurium HWSH derivatives using different routes of infection. Compared with IL-4^+/+ mice, IL-4^-/- mice exhibited a delayed time to death following infection with wild-type S. typhimurium HWSH. Croups of IL-4^+/+ mice infected with S. typhimurium HWSH purE, a less virulent derivative, showed sporadic deaths and harbored micro- or macroabscesses in their tissues, particularly associated with the liver. However, IL-4^-/- mice infected with similar doses of S. typhimurium HWSH purE bacteria were resistant to killing and failed to develop detectable abscesses. Abscess formation in IL-4^-/- mice could be induced by i.v. administration of rlL-4 during the S. typhimurium HWSH purE infection. The immune response in both IL-4^-/- and 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.