IL18 and infection: After infection, IFN-γ, mainly produced by NK cells and CD4+ T cells, stimulates macrophage activation, inducing high level of Th1 proinflammatory cytokines (e.g., IL-12, IL-2, IL-18, IL-27) and low levels of anti-inflammatory molecules (Spellberg and Edwards, 2001; Varma et al., 2002; Souza-Fonseca-Guimaraes et al., 2012; Kanevskiy et al., 2013).