Background IL-15 is a proinflammatory cytokine that contributes to local inflammation and joint damage in RA. A locally overproduced IL-15 may be responsible for the activation and proliferation of T cells in situ, reflected by significantly increased number of activated T cells in RA possibly contributing to the pathogenesis of RA (Kuca-Warnawin, 2011).
Objectives The aim of the study was to evaluate the clinical significance of serum (S) and synovial fluid (SF) interleukin (IL)-15 measurements in relation to laboratory and clinical measures of disease activity of patients with rheumatoid arthritis (RA).
Methods Forty-four patients with RA (22 in activity) and (22 in remission) and 12 patients with osteoarthritis (OA) were included in this study. RA activity was determined using the Disease Activity Score (DAS) 28 index. Concentrations of IL-15 were measured by ELISA. Serum C-reactive protein (CRP) levels were also determined. Cross-sectional correlations between S and SF levels of cytokine and values of DAS 28 index were calculated.
Results The results have shown that IL-15 levels in S and SF of patients with RA were significantly higher than the levels obtain from patients with OA (p<0.001). S IL-15 level was higher in active group than remission group (P<0.05). Significantly higher S and SF levels of IL-15 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). S IL-15 was higher in RA with positive RF (P<0.05). Positive correlation between SF IL-15 and RF in active RA was found (P<0.01). Serum and SF concentrations of IL-15 positively correlated with DAS 28 index values, i.e., disease activity. ESR and duration of morning stiffness were correlated with S and SF IL-15 in active RA (P<0.05), but no correlation with duration of the disease. Serum IL-15 was found to be positively correlated with SF IL-15 in RA patients in activity.
Conclusions In conclusion, SF IL-15 levels in RA patients are good indicators of disease activity. The results obtained support the contribution of its use in clinical practice as a reliable method in assessing disease activity in RA patients.
Elevated number of recently activated T cells in bone marrow of patients with rheumatoid arthritis: a role for interleukin 15? Kuca-Warnawin E, Ann Rheum Dis 01-JAN-2011; 70(1): 227-33.
Disclosure of Interest None Declared