Maternal and umbilical cord serum interleukin levels in preterm labor with clinical chorioamnionitis

Our purpose was to determine whether interleukin-1 beta, interleukin-6, and the soluble receptor for interleukin-2 levels in maternal and umbilical cord sera differed among patients with and without clinical chorioamnionitis delivered prematurely.

Between February and November 1992, 32 women who were delivered between 20 and 36 weeks' gestation were enrolled in a prospective study to determine the levels of interleukin-1 beta, soluble interleukin-2 receptor, and interleukin-6 in maternal and umbilical cord serum. Cytokines were measured by enzyme-linked immunosorbent assay. Chorioamnionitis was identified by the presence of clinical markers in 12 patients.

Soluble interleukin-2 receptor concentrations in maternal serum were significantly higher in women with clinical chorioamnionitis than in those without chorioamnionitis (median 400 U/ml, range 100 to 2100 U/ml vs median 275 U/ml, range 100 to 1300 U/ml, p < 0.04). Umbilical cord interleukin-6 concentrations were significantly higher in the presence of clinical chorioamnionitis than in the absence of chorioamnionitis (median 12.5 pg/ml, range 0 to 400 pg/ml vs median 0 pg/ml, range 0 to 25 pg/ml; p < 0.02). For patients with clinical chorioamnionitis there was a positive correlation between maternal and umbilical cord IL-2 receptor levels (r = 0.752, p < 0.01). No significant differences in maternal interleukin-1 beta or maternal interleukin-6 determinations were noted. Likewise, the umbilical cord interleukin-1 beta and IL-2 receptor concentrations were unchanged in the presence of clinical chorioamnionitis.

This study demonstrates that for patients with preterm labor and clinical chorioamnionitis, maternal serum levels of IL-2 receptor, and umbilical cord serum levels of interleukin-6 are significantly increased compared with patients without chorioamnionitis.