title: The correlation between increased serum concentrations of interleukin-6 family cytokines and disease activity in rheumatoid arthritis patients.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  We obtained serum samples from 40 patients with RA and 40 age- and sex- matched healthy controls, and we assessed the clinical parameters of disease activity, including the 28-joint disease activity score (DAS28) and C-reactive protein (CRP) levels. Serum samples from five patients with high disease activity (DAS28 > 5.1) were also collected at the eighth week of treatment. Serum concentrations of IL-6, IL-11, and leukemia inhibitory factor (LIF) were measured using an enzyme-linked immunosorbent assay (ELISA).
  
  
  RESULTS
  Serum concentrations of IL-6 family cytokines, including IL-6, IL-11, and LIF, were significantly elevated in patients with RA compared to those of healthy controls. Although there was no significant relationship between IL-6 family cytokine levels and DAS28, the IL-6 levels of patients with RA showed a significant correlation with CRP levels. After eight weeks of medical treatment in patients with high disease activity, a decrease in DAS28 was associated with a significant decrease in the serum concentrations of IL-6 and IL-11.
  
  
  CONCLUSIONS
  The serum concentrations of IL-6 family cytokines were significantly elevated in patients with RA, and they decreased with medical treatment. These findings suggest a possible role for IL-6 family cytokines in the pathogenesis of RA.
authors.affiliation: 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.
authors.forename: Soo-Jin
authors.initials: SJ
authors.lastname: Chung
authors.forename: Yong-Jin
authors.initials: YJ
authors.lastname: Kwon
authors.forename: Min-Chan
authors.initials: MC
authors.lastname: Park
authors.forename: Yong-Beom
authors.initials: YB
authors.lastname: Park
authors.forename: Soo-Kon
authors.initials: SK
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000097:blood*; D002097:C-Reactive Protein / Q000032:analysis; D016207:Cytokines / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D017370:Interleukin-11 / Q000097:blood; D015850:Interleukin-6 / Q000097:blood*; D053605:Leukemia Inhibitory Factor / Q000097:blood; D008297:Male; D008875:Middle Aged; D055815:Young Adult
chemical_list: D016207:Cytokines; D017370:Interleukin-11; D015850:Interleukin-6; C507837:LIF protein, human; D053605:Leukemia Inhibitory Factor; D002097:C-Reactive Protein