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Clin Rheumatol. 2006 Jul;25(4):448-52. Epub 2005 Dec 14.

Clinical significance of IL-18, IL-15, IL-12 and TNF-alpha measurement in rheumatoid arthritis.

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Clinic of Rheumatology and Clinical Immunology, Military Medical Academy, Belgrade, Serbia and Montenegro.


The aim of the study was to evaluate the clinical significance of serum (S) and synovial fluid (SF) interleukin (IL)-18, IL-15, IL-12 and the tumor necrosis factor alpha (TNF-alpha) measurements in relation to laboratory and clinical measures of disease activity of patients with active rheumatoid arthritis (RA). Sixty-four patients with RA and 25 patients with osteoarthritis (OA) were included in this study. RA activity was determined using the Disease Activity Score (DAS) 28 index. Concentrations of IL-18, IL-15, IL-12 and TNF-alpha were measured by ELISA. Serum C-reactive protein (CRP) levels were also determined. Cross-sectional correlations between S and SF levels of cytokines and values of DAS 28 index were calculated. The results have shown that IL-18, IL-15, IL-12 and TNF-alpha levels in S and SF of patients with RA were significantly higher than the levels obtain from patients with OA (p<0.01). Significantly higher levels of IL-18, IL-15 and TNF-alpha were found in the SF compared to the S of patients with RA (p<0.01). Significantly higher S and SF levels of all four cytokines and serum CRP values were found in RA patients with high disease activity (DAS 28>5.1) compared to those with mild (DAS 28>3.2) and low disease activity (DAS 28>2.6) (p<0.01). Serum and SF concentrations of all four cytokines positively correlated with DAS 28 index values, i.e., disease activity. A poor correlation was found for S and SF IL-12 whereas the highest coefficient of correlation was found for SF IL-18 (r=0.879, p<0.01), and SF TNF-alpha (r=0.827, p<0.01) and disease activity in this study. Strong correlation was found between SF TNF-alpha and SF IL-18 levels (r=0.732, p<0.01). In conclusion, SF IL-18 and TNF-alpha levels in RA patients are good indicators of disease activity. The results obtained support the use of the DAS in clinical practice as a reliable method in assessing disease activity in RA patients.

[Indexed for MEDLINE]

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