The Placental Growth Hormone is Biologically Active

The human pituitary growth hormone (hGH-N) acts on the staturo-ponderal growth and on the lipid and carbohydrate metabolism but also appears to play a part in the regulation of the immune system.
During human pregnancy, the maternal blood concentration of hGH-N decreases whereas that of the placental growth hormone (hGH-V) produced by trophoblastic cells increases. Interestingly, lymphoid cells are able to produce hGH-N and hGH-V and express hGH-N receptors. Here it appears that lymphoid cells can possess hGH-V receptors. The question is thus to know if hGH-V exerts the same effects as hGH-N on the immune system.
In this study, we demonstrate that hGH-V, like hGH-N, is able to promote the proliferation of the IM-9 B cell line. We also observed that hGH-V modulates the proliferation capacity of JEG-3 cells, a choriocarcinoma cell line, which is insensitive to the action of hGH-N. Thus one can suspect a retroaction of hGH-V on the trophoblastic cells.