CTLA4 and rheumatoid arthritis: Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease characterized by synovitis and subsequent inflammatory bone destruction.[1] Previous studies indicate that imbalance between innate and adaptive immune systems can lead to excessive immune responses in rheumatoid synovium.[2] Coinhibitory receptors such as cytotoxic T-lymphocyte-associated protein 4 have an important role in the regulation of T cell responses[3] and are evidently effective targets in RA, in which coinhibitory T cell receptor expression can dampen the effector T cell responses.[4]