Secretion of colony stimulating factor-1 by human first trimester placental and decidual cell populations and the effect of this cytokine on trophoblast thymidine uptake in vitro

The present in-vitro study using an enzyme-linked immunosorbentassay has identified the cell types responsible for colony stimulatingfactor-1 (CSF-1) production at the first trimester human placentaluterine interface. The major sources were observed to be decidualstromal cells and decidual CD56⁺ natural killer (NK) cells,but decidual CD3⁺ T cells did not produce CSF-1, reflectingfunctional differences between these two decidual lymphoid populations.Of a variety of cytokines tested, only interleukin-2 (IL-2)was found to augment CSF-1 secretion by decidual NK cells. Trophoblastcells also secreted CSF-1, but the amounts were small relativeto decidual stromal cells and NK cells. Therefore, most of theCSF-1 present at the implantation site appears to be maternallyderived. Co-culture of decidual NK cells on a monolayer of irradiatedtrophoblast did not augment CSF-1 secretion by decidual NK cells,indicating that the production of this cytokine is not stimulatedby contact with fetal trophoblast. CSF-1 was found to increase[³H]thymidine uptake by trophoblast cultured on laminin for72 h, but no such response was seen in trophoblast culturedon fibronectin, indicating that these extracellular matrix proteinshave differential effects on the response of trophoblast tothis cytokine.