Interleukin-6 and interleukin-1 receptor antagonist in amniotic fluid and cord blood in patients with pre-term, premature rupture of the membranes

Objective: We investigated the role of interleukin (IL)-6 and IL-1 receptor antagonist (IL-1ra) in pre-term premature rupture of the membranes (PROM). Method: Amniotic fluid samples were collected from 10 patients with pre-term PROM (group 1a), 13 patients undergoing genetic amniocentesis (group 2), seven patients with normal vaginal delivery (group 3a), and 11 patients with elective cesarean section (group 4a). Umbilical venous blood was collected from nine cases of pre-term PROM (group 1b), 19 cases of normal delivery (group 3b) and nine cases of elective cesarean section (group 4b). Results: The concentration of IL-6 in the amniotic fluid in group la was significantly higher than in group 2 (P < 0.001), and that in group 3a was significantly higher than in group 4a (P < 0.001). The concentration of IL-1ra in amniotic fluid in group la was significantly higher than in group 2 (P < 0.001). The concentrations of IL-6 in umbilical venous blood were not significant among the groups. The concentration of IL-1ra in umbilical venous blood in group 1b was significantly higher than in group 3b (P < 0.05) and group 4b (P < 0.05). Conclusions: High concentrations of amniotic fluid IL-6 present in pre-term PROM, are indicative of intrauterine inflammation, probably due to sub-clinical infection. The high concentrations of IL-1ra in amniotic fluid and umbilical venous blood suggest the possibility that the presence of this anti-inflammatory cytokine serves to prevent the development of overt inflammation. (C) 2002 International Federation of Gynecology and Obstetrics. Published by Elsevier Science B.V. All rights reserved.