Lowering Cholesterol With Granulocyte-Macrophage Colony-Stimulating Factor

To the Editor.—  We read with interest the report by Nimer and coworkers¹ demonstrating that granulocyte-macrophage colony-stimulating factor (GM-CSF) lowers serum cholesterol when administered by infusion to patients with aplastic anemia. The authors postulate a number of potential mechanisms whereby GM-CSF may alter cholesterol metabolism. We agree with their hypothesis that the action of GM-CSF on hepatic cholesterol biosynthesis is most likely indirect and mediated via liver cells of monocyte-macrophage lineage. However, we would like to suggest an alternative mechanism not addressed in their report.We propose that the hypocholesterolemic effect of GM-CSF is related to the simulation of inflammatory cytokines. Sisson and Dinarello² have recently demonstrated that recombinant GM-CSF stimulates the production of interleukin 1α, interleukin β, and tumor necrosis factor from normal human mononulcear cells. Interleukin 1, the protein mediator of the acute phase response, has a number of metabolic effects, including stimulation of resting energy