Yonsei Med J.  2011 Jan;52(1):113-120. 10.3349/ymj.2011.52.1.113.

The Correlation between Increased Serum Concentrations of Interleukin-6 Family Cytokines and Disease Activity in Rheumatoid Arthritis Patients

• Chung SJ
• Kwon YJ
• Park MC
• Park YB
• Lee SK

• KMID: 1106445
• DOI: http://doi.org/10.3349/ymj.2011.52.1.113

Abstract

PURPOSE
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.
MATERIALS AND 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.
CONCLUSION
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.

Keyword

Rheumatoid arthritis; interleukin-6 family cytokines; interleukin-6; interleukin-11; leukemia inhibitory factor

MeSH Terms

Adult
Aged
Aged, 80 and over
Arthritis, Rheumatoid/*blood
C-Reactive Protein/analysis
Cytokines/*blood
Enzyme-Linked Immunosorbent Assay
Female
Humans
Interleukin-11/blood
Interleukin-6/*blood
Leukemia Inhibitory Factor/blood
Male
Middle Aged
Young Adult

Figure

• 

  Fig. 1 A comparison of serum concentrations of IL-6, IL-11, and LIF between the two groups. Serum concentrations of IL-6, IL-11, and LIF were significantly higher in the patient group than in the control group. IL, interleukin; LIF, leukemia inhibitory factor.

• 

  Fig. 2 The correlations among serum concentrations of IL-6, IL-11, LIF, and CRP level. (A) Serum concentrations of IL-6 showed a significant positive correlation with CRP levels (r = 0.45, p = 0.007) in RA patients. (B) Serum concentrations of IL-6 showed significant correlations with serum concentrations of IL-11. (C) Serum concentrations of IL-6 showed significant correlations with serum concentrations of LIF. (D) Serum concentrations of IL-11 showed significant correlations with serum concentrations of LIF. IL, interleukin; LIF, leukemia inhibitory factor; CRP, C-reactive protein; RA, rheumatoid arthritis.

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