title: Recombinant human interferon-gamma inhibits formation of human osteoclast-like cells.
abstract: Interferon-gamma (IFN-gamma) inhibits osteoclastic bone resorption in vitro, but the mechanism responsible for this inhibition is unknown. We have used a long-term human marrow culture system that forms multinucleated cells (MNC) with osteoclast characteristics to test the effect of recombinant human IFN-gamma on MNC formation. The addition of 1,25-dihydroxy-vitamin D3 (1,25D3) at 10(-8) M to these cultures significantly increased both MNC formation and the number of nuclei per MNC. IFN-gamma at 100 U/ml strongly inhibited both of these effects of 1,25D3 in this system. IFN-gamma significantly inhibited MNC formation at very low concentrations (4 U/ml), with 10 U/ml inhibiting 1,25D3-stimulated MNC formation by 50%. In contrast, 100 U/ml of IFN-gamma were required to inhibit the growth of granulocyte-macrophage colony-forming cells, the probable progenitor for MNC, by 50%. Treatment of cultures with IFN-gamma for only the first or last week of culture significantly inhibited MNC formation stimulated by 1,25D3. Autoradiographic studies with [3H]thymidine showed that IFN-gamma did not inhibit proliferation of precursors for MNC. Additionally, IFN-gamma inhibited MNC formation stimulated by parathyroid hormone or interleukin 1. These results suggest that IFN-gamma inhibits MNC formation, and that IFN-gamma inhibits bone resorption in part by inhibiting osteoclast formation.
mesh_terms: D001854:Bone Marrow Cells; D001862:Bone Resorption / Q000187:drug effects*; D002117:Calcitriol / Q000494:pharmacology; D003114:Colony-Forming Units Assay; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D007375:Interleukin-1 / Q000494:pharmacology; D010010:Osteoclasts / Q000187:drug effects*; D010281:Parathyroid Hormone / Q000494:pharmacology; D011994:Recombinant Proteins; D013997:Time Factors
chemical_list: D007375:Interleukin-1; D010281:Parathyroid Hormone; D011994:Recombinant Proteins; D007371:Interferon-gamma; D002117:Calcitriol