IFNB1 and serum lipopolysaccharide activity: Pretreatment with IFN-β (1000 units/20 g) 30 min before LPS or CLP challenge significantly improved the survival rates after LPS-induced endotoxemia or CLP-induced sepsis (80% and 63%), compared with control mice(45% and 9%) on day 15 (Fig. 4B) (log-rank test, P < 0.05).