Interleukin (IL)–12 and IL-23 Are Key Cytokines for Immunity against Salmonella in Humans

Patients with inherited deficiency of the interleukin (IL)–12/IL-23–interferon (IFN)–g axis show increased susceptibility to invasive disease caused by the intramacrophage pathogens salmonellae and mycobacteria. We analyzed data on 154 patients with such deficiency. Significantly more patients with IL-12/IL-23–component deficiency had a history of salmonella disease than did those with IFN-g–component deficiency. Salmonella disease was typically severe, extraintestinal, and caused by nontyphoidal serovars. These findings strongly suggest that IL-12/IL-23 is a key cytokine for immunity against salmonella in humans and that IL-12/IL-23 mediates this protective effect partly through IFN-g–independent pathways. Investigation of the IL-12/IL-23–IFN-g axis should be considered in patients with invasive salmonella disease.