HCG SECRETION BY PERIPHERAL MONONUCLEAR-CELLS DURING PREGNANCY

Peripheral mononuclear cells (MNC) in culture release a biologically a ctive hCG. This effect is detectable during pregnancy with a maximum b etween the 9th and 16th wk. Peripheral MNC already secrete hCG between the 7th and 11th d after embryo transfer. The secretion of hCG is act ivated by the PKC-activator TPA. TPA induces hCG release into the medi um, thus causing a decrease in intracellular hCG content. In contrast, db-cAMP inhibites hCG secretion into the medium. Protein synthesis in hibitors of transcription and translation suppress the production and secretion of hCG. Peripheral natural killer (NK) cells (CD 56+/CD16+) and monocytes (CD14+) show the highest secretion rates. IL-1 beta, IL- 4, IL-6, IL-10, TNF alpha, and GM-CSF stimulate, whereas IL-2 and INF gamma inhibit, the hCG secretion of mononuclear cells. Flow cytometric experiments with hCG antibody demonstrate a binding of hCG on the sur face of monocytes more than lymphocytes. The binding capacity is impro ved during pregnancy. Different hCG bands are shown in the Western blo t analysis. We could confirm the mRNA of beta hCG and alpha CG are in MNC as well in the placental control. Peripheral MNC, first and foremo st NK cells and monocytes, produce and secrete hCG during pregnancy, w hich play an important role for the corpus luteum rescue during the ea rly gestational age and possibly for the immunotolerance. (C) Elsevier Science Inc. 1998