Progesterone Enhancement of Prostaglandin E2 Production by Fetal Placental Macrophages

ABSTRACT: The role of progesterone in immunoregulation at the fetomaternal interface at physiological concentrations (2–6 μg/ml) is controversial. This study examines the effect of progesterone on maternal lymphocyte proliferation in a one‐way mixed lymphocytic reaction (MLR) stimulated by allogenic lymphocytes as well as on prostaglandin production and secretion by fetal placental macrophages. No suppressive effect on maternal lymphocyte proliferation was found at progesterone levels of up to 20 μg/ml. However, physiological concentrations of progesterone were found to induce a significant increase in the fetal macrophage release of PGE₂, which is well known as a strong immunosuppressant. PGI₂ production and secretion by these cells, measured by the appearance of its 6‐ket‐PGF₁α product, was not affected by incubation with progesterone. Enhancement of PGE₂ secretion by progesterone may partly explain the roles of progesterone and fetal placental macrophages in immunosuppression at the fetomaternal interface. 1987 Munksgaard