A) Experimental Design: NCR1-CreERT2+/− IL-10flox/flox Rosa26-TdTomato Thy1.1/1.1 and IL-10flox/flox Rosa26-TdTomato Thy1.1/1.1 mice were administered tamoxifen in corn oil daily, for 3–5 days, by oral gavage. Two days after the last tamoxifen dose mice underwent CLP20 surgery. Mice were then monitored for morbidity, by both weight loss and clinical scoring, and mortality. Representative flow profiles demonstrating successful Cre-mediated excision of LoxP sites on the day of surgery by assessing the frequency of (B) TdTomato-expressing cells among NK cells from IL-10flox/flox Rosa26-TdTomato Thy1.1/1.1 mice as wells among T cells and NK cells from NCR1-CreERT2+/− IL-10flox/flox Rosa26-TdTomato Thy1.1/1.1 mice and by assessing or (C) NK cells among both singlets and TdTomato-expressing cells in NCR1-CreERT2+/− IL-10flox/flox Rosa26-TdTomato Thy1.1/1.1 mice. (D) Weight loss, (E) mortality, and (F) clinical scoring of following CLP20 surgery of IL-10flox/flox Rosa26-TdTomato Thy1.1/1.1 mice (NK-IL10 sufficient) and NCR1-CreERT2+/− IL-10flox/flox Rosa26-TdTomato Thy1.1/1.1 (NK-IL10 deficient) mice. (G) Plasma IL-10 concentration of IL-10flox/flox Rosa26-TdTomato Thy1.1/1.1 mice (NK-IL10 sufficient) and NCR1-CreERT2+/− IL-10flox/flox Rosa26-TdTomato Thy1.1/1.1 (NK-IL10 deficient) mice 12hrs after CLP20 surgery. Morbidity and mortality data are combined from 2 independent experiment with 22–24 mice per group. Mortality data is displayed as Kaplan-Meier curves. Cytokine data are from a single experiment with 10–11 mice per group. * = p<0.05. Error bars represent standard error of the mean.