This study was performed to determine whether the serum concentrations of interleukin (IL)-6 family cytokines are elevated in patients with rheumatoid arthritis (RA) and to investigate the relationship between IL-6 family cytokine levels and disease activity in RA patients.
Division of Rheumatology, Department of Internal Medicine, Institute for Immunology and Immunologic Disease, Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea.