IL6 and rheumatoid arthritis: Cytokines secreted by RA synoviocytes include tumor necrosis factor-α (TNF-α), interleukin-1α (IL-1α), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), and granulocyte macrophage-colony stimulating factor (GM-CSF) [3].