TNF and rheumatoid arthritis: IL-1 and TNF-α are major proinflammatory cytokines in RA joints and stimulate IL-6 production by synovial fibroblasts [33-37], whereas IL-6 is a major circulating cytokine in RA that induces the acute phase response, production of immunoglobulins by B cells and neuroendocrine alterations [33,34,37,38].