Amniotic fluid soluble Fas levels in intra-amniotic infection

Objective: Membrane Fas can induce apoptosis in sensitive cells. It has been reported that soluble Fas (sFas) is elevated in septicemia. We examined amniotic fluid (AF) sFas levels in patients with and without intra-amniotic infection. Methods: Forty-two AF specimens were studied. Intraamniotic infection was defined as the presence of a positive AF culture. Twenty-one specimens were from patients with intra-amniotic infection and 21 were from patients without intra-ammotic infection. Amniotic fluid sFas was determined by an enzyme immunoassay and normalized by AF creatinine levels. The Mann-Whitney U test, contingency table method, and Spearman's rank correlation test were used for statistical analyses. Data were expressed as median with ranges. Results: There were no significant differences in maternal age, gestational age, parity, and race between the groups. The median AF sFas was significantly higher with intraamniotic infection than without it (5.07 U/mL, range 0.32-13.25 compared with 1.95 U/mL, range 0.01-5.35; P =.004). After normalizing to AF creatinine, infected fluids also had significantly higher median sFas/creatinine than uninfected amniotic fluids (289.1 U/mg creatinine, range 16.6-920.5 compared with 126.8 U/mg creatinine, range 0.5-546.2; P =.01). Amniotic fluid sFas and sFas/creatinine were positively correlated with AF leukocytes and negatively correlated with AF glucose. Conclusion: Elevated AF sFas is associated with intraamniotic infection. High production of AF sFas in intraamniotic infection may play a role in the inhibition of apoptosis of AF leukocytes, leading to the persistence of inflammation. (Obstet Gynecol 2000;95:667-670. (C) 2000 by The American College of Obstetricians and Gynecologists.).