IL1B and chorioamnionitis: The intra-amniotic injection of IL-1β and TNF-α induces histologic chorioamnionitis characterized by extensive neutrophil infiltration and patchy necrosis in the chorion layer and preterm labor in rhesus monkeys, while the intra-amniotic injection of IL-6 induces histologic chorioamnionitis characterized by macrophage infiltration and patchy necrosis but not preterm labor [145].