IFN-ζ /limitin Inhibits Generation of Osteoclast Precursors

I nterferon (IFN)-ζ /limitin, a type-I IFN, was originally cloned on the basis of selective inhibitory effect on B-lineage cells. Ovariectomy of mice have been known to augment the number of osteoclast precursors and B220 + pre-B cells. Here, we examined whether estrogen deficiency decreases the production of IFN-ζ /limitin and whether IFN-ζ /limitin inhibits osteoclast precursor generation. IFN-ζ /limitin mRNA expression was increased in ovariectomized-mouse femur. IFN-ζ /limitin decreased osteoclastogenesis from B220 + cells induced by 1,25-dihydroxyvitamin D3 in cocultures of B220 + + cell proliferation. IFN-ζ /limitin also inhibited macro- phage lineage osteoclast precursors without affecting macrophage generation. IFN-ζ /limitin had no effects on LPS-induced NO production by mature macrophages. These data indicated that IFN-ζ /limitin inhibits osteoclast precursor generation without affecting macrophage generation and functions.