IL6 and rheumatoid arthritis: The interleukin (IL)-1 (family) together with its members (IL-33, IL-36α, β, γ, IL-37, and IL-38), IL-6, and IL-12 superfamilies (IL-27, IL-35) together with the other key cytokines (IL-15, IL-16, IL-17 family IL-17A, IL-17B, IL-17C), the recently cloned cytokine IL-18, IL-32, IL-34, and interferon (IFN)-y, the granulocyte macrophage colony-stimulating factor, are detected in a high concentration in the synovial fluid, but also in the patient’s serum, thus leading to the process of local joint destruction and systemic effects in the rheumatoid arthritis patient [79,89].