Characterization of cells cultured from human giant-cell tumors of bone. Phenotypic relationship to the monocyte-macrophage and osteoclast

Cell culture techniques were used to clarify the histogenesis of giant-cell tumor of bone. Even after passage, nearly all of the mononuclear cells possessed tartrate-resistant acid phosphatase and receptors for eel calcitonin, which are both phenotypic markers for osteoclasts. Eel calcitonin produced an increase in the cyclic adenosine monophosphate (cAMP) content of the mononuclear cells. More than 90% of mononuclear tumor cells expressed monocyte markers; flow cytometric C3b receptor, a macrophage marker, was also detected in a few cells. These findings demonstrate that the mononuclear cells expressed phenotypes of both the osteoclast and monocyte-macrophage and that they originate in a monocyte-macrophage-osteoclast lineage. Giant-cell tumor of bone may thus provide a good model for investigating the mechanism of bone resorption in which cells of osteoclast lineage play a central role.     

Evidence that ciclosporin is hepatotoxic and hepatotrophic in 70% hepatectomized rats and mice

The influence of ciclosporin (Cs) on liver regeneration was studied in rats and mice with or without thymus after two-third hepatectomy. Rats were treated at -24, 0, and +24 h posthepatectomy with oral Cs, 5, 10, or 20 mg/kg. Before hepatectomy, mice were given a 4-day course of Cs 10 mg/kg. The peak mitosis (30 h posthepatectomy) of remnant hepatocytes in rats was doubled by the two lower dosages of Cs but was suppressed by the highest dosage compared with control. In addition, the rise in serum transaminase and total bilirubin concentrations was proportionate to the increase in Cs dosage given. Cs increased hepatocyte division in thymic mice but was hepatotoxic in athymic nude mice. These data present evidence that Cs is both hepatotrophic and hepatotoxic in regenerating liver.