CD4 and infection: While IL-1β is shown to be a potent proinflammatory cytokine that is crucial for host-defense to infection and injury, but also for the polarization of CD4+ T cells and the activation and differentiation of antigen-specific CTL (Dinarello, 1996; Nambu et al., 2006; Ben-Sasson et al., 2013; Garlanda et al., 2013), IL-18 is demonstrated to induce the differentiation of CD4+ to T helper cells 1 (Th1) and Th2, regulating their immune responses, and to drive NK cell and CTL activity through the promotion of IFNγ production (Xu et al., 2000; Nakanishi et al., 2001; Dupaul-Chicoine et al., 2015).