Lactoferrin Decreases Monocyte - Induced Fibroblast Production of Myeloid Colony - Stimulating Activity by Suppressing Monocyte Release

Lactoferrin (If) is a negative regulator of myelopoiesis which operates by suppressing the release from mononuclear phagocytes of GM colony-stimulating factor (GMCSF) or monokines which can then induce the release of GM-CSA from accessory cells. In this study. endotoxindepleted. purified iron-saturated human If was assessed for its effect on the production of interleukin-1 by cultured monocytes and their subsequent effect on colony-stimulating factor release from cultured fibroblasts. Monocytes were grown with or without If and If that had previously been incubated with monoclonal anti-If. The monocyteconditioned medium was then either assayed for the presonce of interleukin-1 (Il-i ) with an enzyme-linked immunosorbent assay or for its ability to stimulate fibroblasts to release growth factors for CFU-GM. BFU-E. or CFU-Mix colonies. In the presence of If (iO or i0 mol/I). GM colony-stimulating activity (GM-CSA) was suppressed by