Two cell types isolated and purified to homogeneity from human decidua obtained at 8-17 weeks of gestation were shown immunocytochemically to correspond to decidual and epithelial cells in the tissue of origin. The decidual cells reacted with antihuman PRL antiserum, and epithelial cells reacted with antiserum against keratin, an epithelial cell marker. Decidual and epithelial cells were cultured separately to determine their abilities to release PRL to the medium. Decidual cells released 140-410 ng PRL/mg protein in 24 h, whereas no PRL was detectable in cultures of isolated epithelial cells. These homogeneous preparations provide an excellent system with which to study the regulation of PRL production and other biochemical properties of decidual components.

Homogeneous preparations of decidual cells were obtained from term decidual tissue adherent to fetal membranes by using a slightly modified version of a technique developed for the isolation of decidual cells from first and second trimester decidua. The effects of human PRL (hPRL) and oxytocin on the kinetics of the hydrolysis of estrone sulfate were determined in decidual cells prepared from tissue obtained before and after the onset of labor. In addition, sulfatase activity in decidual cells isolated from term decidua was compared with those of chorionic cells isolated from chorion leave of the same pregnancy. Chorionic cells had significantly higher (mean, 2.5-fold) levels of sulfatase activity than the corresponding decidual cells. The mean sulfatase activity in decidual cells obtained after normal vaginal delivery [25 +/- 19 (+/- SE) nmol/mg protein X 15 min) was higher than that in decidual cells obtained from patients undergoing cesarean section before the onset of labor (1.7 +/- 0.11). This difference was significant (P less than 0.02, by Mann-Whitney test) in spite of the large variation in activity in preparations from vaginal deliveries. hPRL (500 ng/ml) and oxytocin (0.2 microM) had similar effects on sulfatase activity in decidual cells in a manner dependent on whether the cells were isolated from tissue obtained before or after labor. In cells isolated from fetal membranes obtained before labor (cesarean delivery), hPRL or oxytocin significantly stimulated sulfatase activity, whereas in decidual cells obtained after vaginal delivery, both hPRL and oxytocin significantly inhibited sulfatase activity. The Michaelis constants for the hydrolysis of estrone sulfate (Km, 22 +/- 4.8 microM) were not affected by these hormones. Since the mean sulfatase activity of decidual cells obtained before labor was approximately 10-fold higher than the activity reported for endometrial stromal cells, PRL produced by decidual cells may act in vivo as an autocrine factor to stimulate their sulfatase activity.