The effects of colony stimulating factors on human monocyte cell function

We used a panel of functional assays to compare directly the pattern and potency of GM-CSF and M-CSF on monocyte activity associated with cell-mediated immune defense. GM-CSF and M-CSF were found to be equivalent both in their capacity to stimulate human monocyte functions in vitro and in their pattern of monocyte activation. The two CSFs were effective in inducing monocyte chemotaxis towards either fMLP or LTB4 at equivalent concentrations across a panel of donors. GM-CSF and M-CSF demonstrated equipotency in the induction of monocyte phagocytosis of heat-killed baker's yeast and in the regulation of the hexose-monophosphate shunt (NBT reduction). Both were also found to be equivalent in preventing steroid (dexamethasone)-induced suppression of monocyte anti-bacterial (Candida albicans) and anti-fungal (Staphylococcus aureus) phagocytic capacities. GM-CSF was somewhat more effective than M-CSF in stimulating monocyte C. albicans killing at a lower E:T ratio.