Neutrophil attractant/activating peptide-1/interleukin-8: association with histologic chorioamnionitis, preterm delivery, and bioactive amniotic fluid leukoattractants

Abstract

Objectives: The goals of this study were (1) to determine immunoreactive neutrophil attractant/activating peptide-1/interleukin-8 levels in amniotic fluid from patients with preterm labor and (2) to compare neutrophil attractant/activating peptide-1/interleukin-8 levels, amniotic fluid culture, Gram stain, and the leukotaxis bioassay for their ability to predict histologic chorioamnionitis and clinical outcome.

Study design: Amniotic fluid was collected by amniocentesis from 55 patients with idiopathic preterm labor and three patients with preterm labor and clinical chorioamnionitis. Gram stain, culture (aerobic, anaerobic, and Mycoplasma species), leukotaxis bioassay, and a commercially available neutrophil attractant/activating peptide-1/interleukin-8 enzyme-linked immunosorbent assay (sensitivity 1 ng/ml) were performed on the amniotic fluid samples. Placentas and chorionic membranes were evaluated for evidence of histologic chorioamnionitis in patients delivered preterm.

Results: All patients with detectable leukoattractants by the leukotaxis bioassay had neutrophil attractant/activating peptide-1/interleukin-8 levels above the threshold of the assay. The presence of amniotic fluid neutrophil attractant/activating peptide-1/interleukin-8 is a more sensitive marker for histologic chorioamnionitis and delivery before 34 weeks than is amniotic fluid culture (100% vs 59%, p < 0.01; and 95% vs 56%, p < 0.01, respectively). Also, of patients in idiopathic preterm labor those without amniotic fluid leukoattractants (group 1) had the lowest amniotic fluid levels, followed by patients with amniotic fluid leukoattractants and a negative culture (group 2) and patients with amniotic fluid leukoattractants and a positive culture (group 3) who had the highest levels (group 1 vs group 2, p < 0.001; group 2 vs group 3, p < 0.01).

Conclusions: Amniotic fluid neutrophil attractant/activating peptide-1/interleukin-8, like the leukotaxis assay, is an accurate antepartum predictor of histologic chorioamnionitis and subsequent early delivery in patients with preterm onset of labor. This study supports the role of neutrophil attractant/activating peptide-1/interleukin-8 in the recruitment of neutrophils into chorionic membranes and placenta during developing intrauterine infection.