IL21 and rheumatoid arthritis: In fact, it has been demonstrated that cytokines including IL-1 beta (IL-1β), IL-2, IL-3, IL-6, IL-7, IL-8, IL-12, IL-15, IL-17, IL-18, IL-19, IL-20, IL-21, IL-23, IL-32, IL-33, IL-35, TNF, interferon-alpha/gamma (IFN-α/γ) and granulocyte-macrophage colony-stimulating factor (GM-CSF) have important roles in RA physiopathology as they contribute to the induction and maintenance of inflammation (13, 27–30).