Leukocytes infiltrate the myometrium during human parturition: further evidence that labour is an inflammatory process

Inflammatory mediators in the cervix, placenta and fetal membranes play a c rucial role in human parturition, The aim of this study was to determine wh ether the upper and lower segments of the myometrium are infiltrated by inf lammatory cells during pregnancy and parturition, Myometrial biopsies were obtained from non-pregnant women, and pregnant women at term before and aft er the onset of spontaneous labour. Subpopulations of inflammatory cells we re identified using immunocytochemistry, The intercellular adhesion molecul es, 1 and 2, platelet endothelial cell adhesion molecule, vascular cell adh esion molecule and E-selectin were immunolocalized to investigate their inv olvement in leukocyte accumulation. Histological analysis demonstrated that inflammatory cells, predominantly neutrophils and macrophages, infiltrate human myometrium during spontaneous labour at term, The infiltrate is predo minant in the lower uterine segment but is also present in the upper segmen t, Increased expression of E-selectin was found on the vascular endothelium of biopsies obtained during labour, suggesting a role for this molecule in the accumulation of leukocytes, These results suggest that inflammatory ce ll infiltration is part of the physiological mechanisms that occur in the m yometrium during parturition, Further understanding of this process may sug gest new strategies aimed at preventing preterm delivery.