CTLA4 and rheumatoid arthritis: Recent advances in our understanding of the pathophysiology of rheumatoid arthritis (RA) have led to the development of new biologic treatments designed to act against a precise therapeutic target: these include tumor necrosis factor-alpha (TNFα), interleukin-1-receptor antagonist (IL1-Ra, anakinra), cytotoxic T-lymphocyte-associated protein 4 (CTLA4-Ig or abatacept (ABA)), CD20 expressed on B cells (rituximab) and IL-6 receptor (tocilizumab) [1].