Granulocyte-macrophage colony-stimulating factor (GM-CSF) reduces toxoplasmastatic activity of human monocytes via induction of prostaglandin E2 (PGE2).

In this study we investigated the effect of human GM-CSF on the toxoplasmastatic activity and release of H2O2 and PGE2 by human monocytes. Incubation of monocytes from healthy controls with GM-CSF resulted in a dose-dependent reduction of toxoplasmastatic activity and a decrease in H2O2 production. Furthermore GM-CSF-treated monocytes released more PGE2 than untreated cells. To investigate the role of PGE2 in the reduced toxoplasmastatic activity of GM-CSF-treated monocytes, these cells were incubated with indomethacin. This resulted in a reduction of PGE2 release and restoration of toxoplasmastatic activity of monocytes treated with GM-CSF. GM-CSF reduces the toxoplasmastatic activity of monocytes via production of PGE2.