Interleukin-6, soluble interleukin-2 receptor and soluble interleukin-6 receptor in the sera of patients with different histological patterns of rheumatoid synovitis

Clin Exp Rheumatol. Jan-Feb 2003;21(1):63-9.


Objective: The present study was conducted to investigate whether the serum levels of interleukin 6 (IL-6), soluble IL-2 receptor (sIL-2R) and sIL-6R are associated with the morphological appearance of rheumatoid arthritis (RA).

Methods: Using the ELISA technique we measured the IL-6, sIL-2R and sIL-6R concentrations in the serum of 34 patients with RA and 28 patients with osteoarthritis (OA). Histological analysis of synovial samples distinguished 2 types of rheumatoid synovitis. Twenty-one RA specimens presented diffuse infiltrates of mononuclear cells without any specific microanatomical organization. In remaining 13 samples the formation of lymphocytic follicles with germinal center-like structures was found.

Results: Serum levels of IL-6, sIL-2R and sIL-6R were elevated in patients with RA compared to the OA control group (p < 0.001, p < 0.001 and p < 0.05 respectively). Concentrations of IL-6 and sIL-2R were highest in the serum of RA patients with follicular synovitis in comparison to patients with diffuse synovitis (p < 0.001 and p < 0.01 respectively) and could distinguish RA patients with these two histological variants of the disease. Serum levels of IL-6 and sIL-2R correlated with markers of disease activity such as ESR and CRP levels. In addition, the clinical data suggest a more severe disease among RA patients with follicular synovitis.

Conclusion: Distinct histological types of rheumatoid synovitis associated with unique serum concentrations of IL-6 and sIL-2R reflect levels of disease activity and confirm the concept of RA heterogeneity.

MeSH terms

  • Arthritis, Rheumatoid / blood*
  • Arthritis, Rheumatoid / complications
  • Arthritis, Rheumatoid / pathology
  • Biomarkers / blood
  • Blood Sedimentation
  • C-Reactive Protein / analysis
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Humans
  • Interleukin-6 / blood*
  • Male
  • Middle Aged
  • Osteoarthritis / blood
  • Osteoarthritis / complications
  • Osteoarthritis / pathology
  • Receptors, Interleukin-2 / blood*
  • Receptors, Interleukin-6 / blood*
  • Synovitis / blood*
  • Synovitis / etiology
  • Synovitis / pathology


  • Biomarkers
  • Interleukin-6
  • Receptors, Interleukin-2
  • Receptors, Interleukin-6
  • C-Reactive Protein