PREECLAMPSIA IS ASSOCIATED WITH DECREASED PLACENTAL INTERLEUKIN-6 PRODUCTION

OBJECTIVE: The etiology of preeclampsia is poorly understood, but may involve abnormal fetal-maternal immunologic interactions. Interleukin-6 (IL-6) is a multifunctional immunologic cytokine that is normally produced by the placenta during pregnancy. Recent studies have shown that amniotic fluid IL-6 is decreased in pregnancies complicated by preeclampsia. Consequently, this study was designed to test the hypothesis that placental IL-6 production is decreased in preeclampsia. METHODS: Placental explants from normal (N = 6) and preeclamptic (N = 6) pregnancies were cultured in vitro, and the media were sampled at 0, 2, 6, 16, 28, and 48 hours. Production rates of IL-6 were measured by enzyme-linked immunosorbent array, and relative IL-6 mRNA expression was measured by Northern and dot blot analyses. RESULTS: Production rates of IL-6 were 2.3-fold lower in preeclamptic placentas than in normal placentas, at 146 pg/mu g/hour versus 341 pg/mu g/hour (P <.05). However, relative steady-state IL-6 mRNA expression was identical in preeclamptic and normal placentas. CONCLUSIONS: Placental IL-6 production is decreased in preeclampsia. The decrease in placental IL-6 production and secretion in preeclampsia is regulated by a post-transcriptional mechanism.