IL4 and Sepsis: Similar to findings obtained with sepsis-surviving Il1rl1−/− mice, the production of IL-4 and IL-13 was markedly reduced in the lungs of Stat6−/− mice on day 15 after CLP (Fig. 3c), indicating that these type 2 cytokines can induce their synthesis in a positive feedback loop in an STAT6-dependent manner.