Fig. 4.

Effect of interleukin (IL)-19, IL-20, and IL-24 on osteoclastogenesis and osteoclast (OC) MCP-1 secretion. a No effect of continuous IL-19, IL-20, and IL-24 stimulation on osteoclastogenesis in cultures of rheumatoid arthritis synovial fluid mononuclear cells (RA SFMCs), as measured by tartrate-resistant acid phosphatase (TRAP) secretion. b IL-20 and IL-24 increased monocyte chemoattractant protein 1 (MCP-1) secretion by OCs generated from RA SFMCs prior to stimulation. Positive controls were stimulated with receptor activator of nuclear factor kappa-B ligand (RANKL) and macrophage-colony stimulating factor (M-CSF) in all experiments. The secretion of TRAP and MCP-1 was calculated as ratios comparing stimulated cells with untreated cells (UT). The ratios were then log transformed and analyzed with paired t-test. Bars indicate the median and whiskers indicate the interquartile range. *P < 0.05