Correlation of a multi-cytokine panel with clinical disease activity in patients with rheumatoid arthritis

Objective: Explore the potential use of a cytokine panel as biochemical markers of disease activity in rheumatoid arthritis (RA) patients. Design and methods: 57 adult RA patients were assessed using five validated clinical disease activity tools: Health Assessment Questionnaire (HAQ), standard 28-joint Disease Activity Score (DAS28), DA528 using C-reactive protein (DAS28-CRP), Clinical Disease Activity Index (CDAI), and Simple Disease Activity Index (SDAI). Plasma cytokine levels (IL-2, IL-4, IL-6, IL-8, IL-10, VEGF, INF-gamma, TNF-alpha, IL1 alpha, IL1 beta, MCP1, and EGF) were measured in 47 of the 57 patients and correlated with clinical indicators. Results: We found significant correlations between plasma levels of IL-6 and all clinical measures of disease activity; Spearman coefficients (p values) were: HAQ: 0.347(0.017); DAS28: 0.409(0.005); DAS-CRP: 0.378(0.011); CDAI: 0.312(0.033); SDAI: 0.310(0.039); ESR: 0.448(0.002); and CRP: 0.513(0.001). IFN-gamma also correlated with DAS-CRP: 0.309(0.039) and SDAI: 0.301(0.044). Furthermore, the levels of IL-6 and IFN-gamma increased significantly with worsening disease, as defined by the European League Against Rheumatism (EULAR) classification of disease activity. Conclusion: A significant correlation between plasma levels of IL-6 and clinical disease activity in patients with RA suggests a future role of IL6 as a disease activity marker. (C) 2010 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.