Injections of anti-CCL9 suppress osteoclast differentiation in vivo.tl/tl rats were injected either with CSF-1 alone or with anti-CCL9 antibody and CSF-1, and TRAP⁺ osteoclasts were counted on multiple sections of the proximal femur from 3 animals for each condition after 4 days of injections. Anti-CCL9 significantly reduced the osteoclastogenic response to CSF-1 injections. Means + 1 SD are shown. In both areas, differences were highly significant (*P < .001).