INDUCTION OF HUMAN OSTEOCLAST-LIKE CELLS BY TREATMENT OF BLOOD MONOCYTES WITH ANTI-FUSION REGULATORY PROTEIN-1 CD98 MONOCLONAL-ANTIBODIES/

We have developed a nem and simple system of human osteoclast formatio n by fusing peripheral blood monocytes with anti-Fusion Regulatory Pro tein-1 (anti-FRP-1) monoclonal antibody (mAb). When human blood monocy tes were cultured in the presence of anti-FRP-1/CD98 mAbs, polykaryocy tes began to appear at approximately 15 h and increased in size with t ime until 3-4 days of incubation with anti-FRP-1 mAb. These fused cell s showed positive staining in tartrate-resistant acid phosphatase, pos sessed numerous calcitonin receptors, and were capable of bone resorpt ion, These results strongly suggest that anti-FRP-1 antibody-induced m ultinucleated cells are osteoclasts. Furthermore, FRP-1 antigens were detected in osteoclasts isolated from human bone and in the osteoclast -like cells obtained from human giant cell tumors of bone.