Interleukin-1beta and interleukin-8 concentrations in the lower uterine segment during parturition at term

Objective: To assess the roles of interleukin-1 beta, interleukin-8, and fibroblasts in the lower uterine segment during parturition. Methods: Lower uterine segment biopsy specimens were obtained from 36 women undergoing cesarean delivery at various stages of cervical dilation (less than 2 cm, n = 8; 2 to less than 4 cm, n = 9; 4-6 cm, II = 10; more than 6 cm, n 9). The concentrations of interleukin-la and interleukin-8 in protein extracts prepared from the tissue samples were measured by enzyme immunoassays. The effect of incubation with interleukin-1 beta (30 U/mL) on interleukin-8 secretion by lower uterine segment fibroblasts in vitro also was determined. Results: The median interleukin-1 beta concentration in the specimens increased from 1.3 pg/mg of total protein at less than 2 cm of dilation to 22.2 pg/mg of total protein at 4-6 cm of dilation (P < .05). No further increase was detectable after 6 cm of dilation. The interleukin-8 concentration increased from 17.2 pg/mg of total protein at less than 2 cm ol: dilation to 2080.7 pg/mg of total protein at 4-6 cm of dilation (P < .05), thus paralleling the increase in interleukin-1 beta concentration. Interleukin-lp induced a significant increase in interleukin-8 secretion by fibroblasts in vitro, from 0.8 ng/10(6) cells to 35.6 ng/10(6) cells. Conclusion: The increase in interleukin-8 concentration in the lower uterine segment during parturition may be induced by interleukin-1 beta and fibroblasts may be one of the sources of this interleukin-8. (C) 1998 by The American College of Obstetricians and Gynecologists.