TNF alpha as a therapeutic target in rheumatoid arthritis.

Rheumatoid arthritis (RA) is an autoimmune disease with inflammatory manifestations in the peripheral synovial joints, which are infiltrated by activated T cells, macrophages, and plasma cells. We have investigated the role of cytokines in RA and have proposed that tumour necrosis factor has a pivotal role in the pathogenesis of this disease. This chapter describes those studies, which led to the first clinical trial in RA patients using a chimeric anti TNF alpha antibody. In addition to pro-inflammatory cytokine production, at sites of inflammation such as the RA synovial joint, there is also evidence for homeostatic immunoregulatory mechanisms which include the production of cytokine inhibitors, such as soluble TNF-R and the IL-1 receptor antagonist, and cytokines with immunoregulatory properties like IL-10. The evidence for these inhibitors in RA is presented, and the relevance of this homeostatic mechanism in relation to chronic inflammatory diseases is discussed.