Correlation Between Increased Serum Concentration of Interleukin-6 and Acute Phase Reactants in Patients with Rheumatoid Arthritis

Abstract

Background: Rheumatoid arthritis (RA) is an inflammatory autoimmune disease that is associated with elevated levels of  pro-inflammatory  cytokines,  particularly  Interleukin-6  (IL-6),  which  enhances  acute  phase  reactants  like  C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR).This study was performed to determine the correlation between elevated levels of IL-6 with the level of acute phase reactants in RA patients.

Methods: RA patients who fulfilled the American College of Rheumatology/European League Against Rheumatism (ACR-EULAR), 2010 criteria were included in the study. Sera samples were collected from 120 RA patients and 100 healthy controls. Commercially available ELISA kit was used to measure CRP and IL-6 levels. ESR was measured using the Westergren method. We used independent sample t-test and Pearson's correlation for the analysis of data.

Results: RA patients had significantly higher serum concentrations of IL-6 and CRP than the healthy controls (p< 0.001). ESR was found to be elevated in RA patients. We found positive correlations of IL-6 with CRP (r=0.635, p<0.001) and ESR (r=0.549; p<0.001). ESR and CRP also showed a positive correlation (r=0.412, p<0.001).

Conclusion: IL-6 was found to be positively correlated with the serum CRP level and ESR in RA patients indicating a central role of IL-6 in the pathogenesis of RA.