Elevated amniotic fluid levels of leukemia inhibitory factor, interleukin 6, and interleukin 8 in intra-amniotic infection

OBJECTIVE: The study's objective was to determine and correlate amniotic fluid levels of leukemia inhibitory factor, interleukin 6, and interleukin 8 in patients with and without intra-amniotic infection. STUDY DESIGN: Amniocentesis was performed on 41 pregnant women with preterm contractions, labor, or premature rupture of membranes. Intra-amniotic infection was defined as the presence of a positive amniotic fluid culture result. Amniotic fluid tests for Gram stain, glucose, leukocyte counts, creatinine level, pH, and specific gravity were performed. Amniotic fluid levels of leukemia inhibitory factor, interleukin 6, and interleukin 8 were measured by an enzyme-linked immunoassay. Unlike in previous reports, cytokines were normalized by amniotic fluid creatinine levels. RESULTS: Fifteen patients had intra-amniotic infection and 26 did not. Amniotic fluid median levels of leukemia inhibitory factor, interleukin 6, and interleukin 8 were significantly higher in pregnant women with intra-amniotic infection than in those without intra-amniotic infection (leukemia inhibitory factor median 3912 pg/mg creatinine, range 0.0-199314, vs 56 pg/mg creatinine, range 0.0-12148, P=.01; interleukin 6 median 2005 ng/mg creatinine, range 27-4071, vs 990 ng/mg creatinine, range 7.5-3409, P=.005; interleukin 8. median 4933 ng/mg creatinine, range 0.0-55058, vs 61 ng/mg creatinine, range 0.0-2399, P=.005). Amniotic fluid levels of leukemia inhibitory factor, interleukin 6, and interleukin 8 were positively correlated. CONCLUSIONS: The data indicate that leukemia inhibitory factor plays an important role in the pathogenesis of intra-amniotic infection. In addition, significant elevations of and correlations among amniotic fluid levels of leukemia inhibitory factor, interleukin 6, and interleukin 8 suggest that measurements of these cytokines in amniotic fluid may be of diagnostic and prognostic importance.