Description
Anti-citrullinated protein antibodies (ACPA) or anti-cyclic citrullinated protein antibodies (anti-CCP) are autoantibodies (antibodies directed against one or more of an individual's own proteins) that are frequently detected in the blood of rheumatoid arthritis patients. The main epitope for these antibodies is filaggrin,and there is cross-reactivity between ACPA and anti-keratin and anti-perinuclear factor.During inflammation, arginine residues in proteins such as vimentin can be enzymatically converted into citrulline ones (a process called citrullination), and, if their shapes are significantly altered, the proteins may be seen as antigens by the immune system, thereby generating an immune response. ACPAs have proved to be powerful biomarkers that allow the diagnosis of rheumatoid arthritis (RA) to be made at a very early stage