Host cytokine response and resistance to infection

Knowledge of the host response, of the resistance process, and of the mediators committed against Salmonella infection is essential to progress towards better means of prophylaxis and eradication. In this context, the present contribution attempts to interconnect, with the pivotal role of the macrophage, the early resistance process under the control of the Nramp1 gene and the cytokine response for resolving infection. IL-12 produced by macrophages is an inducer of IFN-gamma production, which in turn activates the macrophage antibacterial activity and synergizes its effects with TNF-alpha. All three of these cytokines are powerful actors in the first line of anti-Salmonella defence. It can be pointed out that susceptible and resistant individuals do not seem to see the cytokine environment the same way, the former being unresponsive to IL-1 or GM-CSF treatment and deficient in IFN-gamma production. These discrepancies may rely on cell signalling events that could be defective in macrophages of the susceptible phenotype.