Evidence for Progesterone Synthesis by Human Umbilical Cord Blood Erythrocytes

Abstract

In order to determine whether human umbilical cord blood erythrocytes are capable of progesterone biosynthesis, sonicated preparations of plasma-free erythrocytes at the range of total cell numbers between 18.4 × 10⁹ and 62.9 × 10⁹ cells obtained from umbilical cord arterial and venous blood collected from normal pregnant women (n = 6, age 28–39 years) following spontaneous vaginal delivery were incubated with [7n-³H]-pregnenolone as substrate. The leucocyte content of the incubates was negligible (<0.005%). Controls (n = 4, age 29–36 years; 27.6 × 10⁹ to 42.7 × 10⁹ erythrocytes) obtained from cord blood of normal pregnant women were heat-denatured preparations of cells. Using the reverse-isotope dilution technique, [³H]-progesterone was isolated and characterized yielding an overall enzymic conversion which ranged between 0.27 and 0.46%. The results indicate for the first time that cord blood erythrocytes possess the 3β-hydroxysteroid dehydrogenase-5,4-en isomerase activity and are a source of progesterone in human pregnancy.

Progesterone Promotes Differentiation of Human Cord Blood Fetal T Cells into T Regulatory Cells but Suppresses Their Differentiation into Th17 Cells

“…During pregnancy, the placenta becomes a major organ for P4 production. P4 can be produced also by cord blood (CB)2 erythroblasts and is present at high levels in CB (2, 3). While the mechanism is still unclear, P4 is implicated in dampening immune responses to fetal and maternal antigens (4).…”