CHARACTERIZATION OF A CELL-LINE DERIVED FROM A HUMAN GIANT-CELL TUMORTHAT STIMULATES OSTEOCLASTIC BONE-RESORPTION

Giant cell tumors of bone are common but unusual tumors that are compr ised of multiple cell types. Most attention has been focused on the gi ant cells, which resemble osteoclasts morphologically and functionally . This study examines the properties of a cell line derived from monon uclear cells from one of these tumors, since it appears likely that th ese cells may be able to influence the activities of cells with the os teoclast phenotype. This cell line, C433, hast be following characteri stics: (1) it represents undifferentiated cells, not recognized by any known antigenic markers for leukocytes; (2) it contains tartrate-resi stant acid phosphatase; (3) it responds to the osteotropic factors 1,2 5 dihydroxyvitamin D3, insulin-like growth factor I and II, but not to parathyroid hormone; (4) it forms sarcomas in nude mice; and (5) it p roduces an activity that stimulates isolated avian and rat osteoclasts to resorb bone. This cell line may be useful in examining interaction s between osteoclasts and accessory cells involved in bone resorption.