The role of amniotic fluid L-selectin, GRO-α, and interleukin-8 in the pathogenesis of intraamniotic infection

OBJECTIVE: Our purpose was to compare and correlate amniotic fluid GRO-alpha, interleukin-8, and L-selectin in patients with and without intraamniotic infection. STUDY DESIGN: Amniocentesis was performed on 45 pregnant women with preterm contractions, labor, or rupture of membranes. Fourteen patients had intraamniotic infection, and 31 did not. Intraamniotic infection was defined as the presence of a positive amniotic fluid culture. Amniotic fluid tests for Gram stain, glucose, neutrophil counts, creatinine, pH, and specific gravity were performed. Amniotic fluid levels of soluble L-selectin, interleukin-8, and GRO-alpha were measured by an enzyme-linked immunoassay and normalized by amniotic fluid creatinine levels. The Mann-Whitney U test and Spearman's rank correlation test were used for statistical analyses. RESULTS: Amniotic fluid median levels of soluble L-selectin, interleukin-8, and GRO-alpha were significantly higher in pregnant women with intraamniotic infection than in those without intraamniotic infection (soluble L-selectin: median 3334.6 ng/mg creatinine, range 408.4 to 15,956.8 vs 717.2 ng/mg creatinine, range 129.4 to 4601.9, p = 0.009; GRO-alpha: median 841.6 ng/mg creatinine, range 28.1 to 8591.7 vs 56.8 ng/mg creatinine, range 0.0 to 440.2, p < 0.0001; interleukin-8: median 4932.7 ng/mg creatinine, range 0.0 to 55,058.7 vs 28.3 ng/mg creatinine, range 0.0 to 1161.6, p = 0.0004). Patients with intraamniotic infection had significantly higher amniotic fluid leukocyte counts and leukocyte esterase activities and significantly lower amniotic fluid glucose concentrations compared with those without intraamniotic infection. Amniotic fluid GRO-a, interleukin-8, and soluble L-selectin were positively correlated, and each was positively correlated with amniotic fluid leukocytes and negatively correlated with amniotic fluid levels of glucose. CONCLUSIONS: Our data indicate amniotic fluid GRO-alpha and interleukin-8 may be two potent leukocyte chemoattractants and activators, and L-selectin is rapidly shed from leukocytes in the amniotic fluid in patients with intraamniotic infection.