Comparison of CXCL10 concentrations between patients with rheumatoid arthritis (RA) and those with osteoarthritis (OA). CXCL10 concentrations of synovial fluid (a) and sera (b) were measured by enzyme-linked immunosorbent assay. CXCL10 concentrations were significantly increased in synovial fluid and sera of RA in comparison with those of OA. Data were expressed as mean ± standard error. CXCL10, interferon-gamma-inducible protein 10.