Th1 and Th1‐inducing cytokines in Salmonella infection
Thl and Thl‐inducing cytokines and T cell responses were investigated in human salmonellosis. Serum IFN‐γ, IL‐12 and IL‐18 levels were increased significantly in patients with salmonellosis. The increase in serum IL‐15 and IL‐18 levels was more significant and prolonged in patients with the systemic form of salmonellosis than in those with the gastroenteric form. The serum IFN‐γ level was correlated significantly with IL‐12 and IL18 levels, and the IL‐15 level was correlated significantly with IL‐18. Upon stimulation with Salmonella in vitro, mononuclear cells from salmonellosis patients produced significantly higher amounts of IFN‐γ and IL‐12 compared with those from healthy controls. Anti‐IL‐12 moAb or anti‐IL18 MoAb significantly inhibited Salmonella‐induced IFN‐γ production in vitro. γδ T cells expressed significantly higher levels of IFN‐γ mRNA in salmonellosis patients than in healthy controls. The results suggest that Th1‐inducing cytokines appear to be involved in the in vivo response against Salmonella infection, promoting IFN‐γ production by αβ and γδ T cells which plays a protective role against Salmonella.