Labour-associated expression of intercellular adhesion molecule-1 (ICAM-1)in placental endothelial cells indicates participation of immunological processes in parturition

Inflammatory cytokines induce or upregulate de novo expression of cell adhe sion molecules on endothelial and epithelial cells. In order to demonstrate inflammatory reactions within placental tissues in association with normal term as well as non-infection-induced preterm labour, the expression of in tercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and endothelial leucocyte adhesion molecule-1 (ELAM-1) was examin ed by immunohistochemical methods in both trophoblastic villi (n=123) and u mbilical cord (n=61). As a result, ICAM-1 immunoreactivity was exclusively localized in the endothelial cells of the fetal Vascular system, while VCAM -1 and ELAM-1 were not detected. Whereas ICAM-1 was not expressed in early pregnancy (9-12 weeks of gestation), it could be weakly detected at the end of pregnancy in cases of elective caesarean delivery in the absence of lab our, and was significantly more strongly expressed in cases of vaginal deli very after spontaneous onset of normal term labour. Significantly increased immunoreactivity of ICAM-1 within umbilical cord tissues was also found in association with uncontrollable preterm labour in the absence of intrauter ine infection which was excluded after histological examination of fetal me mbranes, umbilical cord and chorionic plate. We conclude that ICAM-1 expres sion in the endothelium of the fetal vascular system is associated with the presence of labour and reflects participation of immune-inflammatory react ions in labour-promoting mechanisms. (C) 1999 Harcourt Publishers Ltd.