Clinical experience of IL-6 blockade in rheumatic diseases—Implications on IL-6 biology and disease pathogenesis

• IL-6 plays a significant role in many rheumatic diseases.
• IL-6 blockade in rheumatoid arthritis, systemic and polyarticular juvenile idiopathic arthritis is clinically effective.
• IL-6 blockade in other rheumatic diseases has shown therapeutic promise in case reports and series.
• IL-6 blockade has not been effective in axial spondyloarthropathies.
• Clinical experience of IL-6 blockade has helped define some of the biological and pathological roles of this cytokine.

Interleukin 6 (IL-6) plays a significant role in many rheumatological diseases and has been described as both a pro- and anti-inflammatory cytokine. IL-6 blockade has been investigated in various rheumatic diseases and a humanised anti-IL-6 receptor antibody has been licensed for use in rheumatoid arthritis, systemic and polyarticular juvenile idiopathic arthritis. The increasing clinical experience of IL-6 blockade in rheumatic diseases adds to the existing knowledge regarding the physiological and pathological roles of IL-6.