Are amniotic fluid neutrophils in women with intraamniotic infection and/or inflammation of fetal or maternal origin?

Abstract

Background Neutrophils are the most abundant white blood cells found in the amniotic cavity of women with intra-amniotic infection and/or inflammation. The current belief is that these neutrophils are of fetal origin. However, abundant neutrophils have been found in the amniotic fluid of women with a severe acute maternal inflammatory response but without a fetal inflammatory response in the placenta, suggesting that these innate immune cells can also be of maternal origin or a mixture of both fetal and maternal neutrophils. Objectives To investigate the origin of amniotic fluid neutrophils from women with intra-amniotic infection and/or inflammation, and to correlate these findings with acute histologic maternal and fetal inflammatory responses in the placenta. Study Design Amniotic fluid was collected from 15 women with suspected intra-amniotic infection and/or inflammation (positive microbiological cultures and/or interleukin (IL)-6 concentrations≥2.6 ng/mL). Amniotic fluid neutrophils were purified by fluorescence-activated cell sorting, DNA was extracted, and DNA fingerprinting was performed. DNA fingerprinting was also performed in the umbilical cord and maternal blood DNA. Fluorescence in situ hybridization (FISH) was assayed in women with male neonates. Blinded placental histopathological evaluations were conducted. Results 1) DNA fingerprinting revealed that 43% (6/14) of the women who underwent a single amniocentesis had mostly fetal neutrophils in the amniotic fluid; 2) DNA fingerprinting showed that 36% (5/14) of the women who underwent a single amniocentesis had predominantly maternal neutrophils in the amniotic fluid; 3) DNA fingerprinting indicated that 21% (3/14) of the women who underwent a single amniocentesis had an evident mixture of fetal and maternal neutrophils in the amniotic fluid; 4) DNA fingerprinting revealed that a woman who underwent two amniocenteses (patient #15) had fetal neutrophils first, and as infection progressed, abundant maternal neutrophils invaded the amniotic cavity ; 5) FISH confirmed DNA fingerprinting results by showing that both fetal and maternal neutrophils are present in the amniotic fluid; 6) Most of the women who had predominantly amniotic fluid neutrophils of fetal origin at the time of collection delivered extremely preterm neonates [71% (5/7)]; 7) All of the women who had predominantly amniotic fluid neutrophils of maternal origin at the time of collection delivered term or late preterm neonates [100% (6/6)]; 8) Two of the women who had an evident mixture of fetal and maternal neutrophils in the amniotic fluid at the time of collection delivered extremely preterm neonates [67% (2/3)], and the third woman delivered a term neonate [33% (1/3)]; and 9) Most of the women included in this study presented acute maternal and fetal inflammatory responses in the placenta [87 % (13/15)]. Conclusion Amniotic fluid neutrophils can be either predominantly of fetal or maternal origin, or a mixture of both fetal and maternal origin, in women with intra-amniotic inf...

The immunophenotype of amniotic fluid leukocytes in normal and complicated pregnancies

“…Previous observations 67, 119 make us suggest that amniotic fluid B cells may be of fetal origin. Fetal pro/pre-B cells can be detected in the omentum as early as 8 weeks of gestation and B-cells can be detected in the liver and spleen at 12 weeks 151 .…”

“…Previous studies have shown that intra-amniotic infection is characterized by the infiltration of neutrophils and monocytes/macrophages 23, 27, 67–69, 129–132 . It was recently suggested that amniotic fluid ILCs were also implicated in regulating intra-amniotic infection and inflammation in preterm gestations 119 .…”

“…It is likely that these adaptive immune cells are derived from the fetus since most of the amniotic fluid leukocytes in early gestation are of fetal origin 67 . In addition, amniotic fluid T cells expressed high levels of RORγt similar to what was observed in amniotic fluid Group 3 ILCs of fetal origin 119 .…”

“…It is likely that amniotic fluid NK cells are derived from the fetus since most of the identified immune cells in this compartment are of fetal origin during this period 67, 119 .…”

“…neural tube defects 118, 120–125 and gastroschisis 118, 126–128 ). The number of amniotic fluid neutrophils, on the other hand, is a useful marker for intra-amniotic inflammation 23, 27, 67–69, 129–132 . However, in the absence of infection and/or inflammation or birth defects, the immune cellular composition of the amniotic fluid is still poorly understood.…”