Amniotic fluid lactoferrin in intrauterine infection

Lactoferrin (LF) has been found in most biological fluids including amnioti c fluid and cervical mucus in pregnant women and is released from neutrophi ls in response to inflammation. It is an important component of the host de fence against microbial infections due to its antimicrobial properties. Pre mature labour is caused by amniotic infection and high concentrations of in flammatory cytokines in amniotic fluid with infection are well established. In the present study, LF levels of intrauterine infection in amniotic flui d were measured and the biological significance of LF was investigated. The effects of LF on IL-6 production in cultured amnion cells were also invest igated. The concentrations of LF and IL-6 in amniotic fluid with chorioamni onitis (CAM) were 8.76 +/- 0.65 mu g/ml and 6.92 +/- 4.88 ng/ml (n= 28), re spectively, and both were significantly higher (P<0.01) than those without CAM (0.86 +/- 0.81 mu g/ml and 0.34 +/- 0.25 ng/ml; n=31). LF and IL-6 leve ls were significantly higher (P<0.01) with CAM. A significant positive corr elation between LF and IL-6 levels in amniotic fluid was found (r=0.91, P<0 .01). To our knowledge, this was the first study of its kind, which shows t hat IL-6 production induced by lipopolysaccharide in cultured cells was sig nificantly inhibited below physiological concentration of LF in the amnion. In addition, the immunohistochemical localization of LF in fetal membranes was investigated. In the fetal membranes with CAM, strong positive stainin g was observed in amniotic and chorionic membranes, with leucocyte migratio n, while weak staining was observed in membranes without CAM. These results show conclusively that LF suppresses amniotic IL-6 production under the co nditions of intrauterine infection. (C) 1999 W. B. Saunders Company Ltd.