ELEVATED AMNIOTIC-FLUID NITRIC-OXIDE METABOLITES AND INTERLEUKIN-6 ININTRAAMNIOTIC INFECTION

OBJECTIVE: To compare amniotic fluid nitric oxide metabolites and inte rleukin-6 (IL-6) concentrations in patients with and without intra-amn iotic infection.METHODS: Amniotic fluid nitric oxide metabolites, IL-6 , Gram stains, glucose, leukocyte counts, leukocyte esterase activity, creatinine, pH, and specific gravity were determined in 14 patients w ith intra-amniotic infection and 26 patients without intra-amniotic in fection. Intra-amniotic infection war defined as the presence of a pos itive amniotic fluid culture. The nitric oxide metabolites, nitrate an d nitrite (NOx), were measured using Greiss reagent after reduction of nitrate to nitrate with aspergillus nitrate reductase. Interleukin-6 was measured by a two-site, enzyme-linked immunosorbent assay. Amnioti c fluid nitric oxide metabolites and IL-6 concentrations were normaliz ed by amniotic fluid creatinine levels. The Mann-Whitney U test, conti ngency table method, and Spearman's rank correlation test were used fo r statistical analyses. RESULTS: Amniotic fluid NOx and IL-6 levels we re significantly higher in patients with intra-amniotic infection than in those without intra-amniotic infection (NOx: median = 2.06 mu mol/ mg creatinine, range = 0.74-6.81 versus 1.35 mu mol/mg creatinine, ran ge = 0.99-1.60, P = .01, IL-6: median = 2.00 mu g/mg creatinine, range = 0.026-4.07 versus median = 0.04 mu g/mg creatinine, range 0.004-3.2 10, P = .0009, respectively). Patients with intra-amniotic infection h ad significantly elevated leukocyte counts, leukocyte esterase activit y, Gram positive stains, and significantly lower amniotic fluid glucos e levels compared with those without intra-amniotic infection. There w ere no differences in gestational age, maternal age, parity, race, pH, or specific gravity between the two groups. Amniotic fluid NOx was si gnificantly correlated with IL-6 (r = .4, P = .02). Both amniotic flui d NOx and IL-6 were also positively correlated with amniotic fluid leu kocyte counts, leukocyte esterase activity and Gram stains, and negati vely correlated with glucose levels. CONCLUSIONS: Amniotic fluid NOx a nd IL-6 are significantly elevated and positively correlated during in tra-amniotic infection. Both increased amniotic fluid IL-6 and nitric oxide may exert cytotoxic and cytostatic effects on the target cells. We suggest that measurements of amniotic fluid NOx and IL-6 may serve as useful clinical markers in patients with intra-amniotic infection. Copyright (C) 1998 by the Society for Gynecologic Investigation.