IL18 and Sepsis: To determine the extent to which intrinsic defects contributed to the impaired production of IFN-γ by NK-cells during L. m. infection, NK-cells obtained from Sham and CLP hosts 48 hours after surgery were stimulated with IL-12 and IL-18 directly ex vivo to bypass sepsis-induced changes in endogenous levels of stimulatory cytokines [19] (Fig 4K).