The relationship between granulocyte elastase-like activity of cervical mucus and cervical maturation.

Granulocyte elastase (elastase)-like activity in 119 samples of cervical mucus from pregnant women was measured. Though elastase-like activity in normal pregnant women was low in 2nd and 3rd trimesters (less than 20 units), it increased during labor (1st stage of labor: 70 +/- 50 U/l; 2nd stage: 72 +/- 56). Elastase-like activity in pregnant women with imminent premature delivery (24-30 gestational weeks) was also high (78 +/- 57). Elastase-like activity of cervical mucus correlated with Bishop score in both normal term and preterm labor. Elastase-containing granulocytes were identified by immunohistochemistry in ripened cervix in normal and preterm labor. Some granulocytes degranulate and release elastase into the cervical stroma. Others migrate through the basement membrane of the endocervix to reach the cervical canal. Elastase could not be demonstrated in immature cervix as assessed by Bishop score. The staining intensity of elastase in the cervix correlated closely with elastase-like activity in cervical mucus. Thus elastase-like activity in cervical mucus reflects the degree of cervical maturation. These results lead one to speculate that elastase is one of the neutral proteases which depolymerize and degrade collagen in the ripening cervix.