Anti-citrullinated protein antibodies: role in pathogenesis of RA and potential as a diagnostic tool

Rheumatoid arthritis is an autoimmune disorder which involves inflammation of the synovial tissue, leading to synovial proliferation, bone erosion and ultimately joint disability. It is a complex disorder, and the proper etiology is still unknown. Both environmental and genetic factors are responsible for the development of rheumatoid arthritis. Clinically, the disease is generally diagnosed by the presence of auto-antibodies like rheumatoid factor. But these are not specifically associated with rheumatoid arthritis. These are also present in patients with other autoimmune disorders and also in healthy persons. Citrullinated epitopes are shown to be more specific for rheumatoid arthritis. Citrullination normally occurs in cells undergoing apoptosis, and hence, citrullinated proteins are cleared from body and not encountered by immune system. However, in rheumatoid arthritis patients, these are not cleared. Anti-citrullinated protein antibodies are detectable in patients at risk of rheumatoid arthritis long before the onset of the disease. The concentration of which normally increases as the disease progress. Hence, these are important for diagnosis of rheumatoid arthritis. This review is focused on the importance of anti-citrullinated protein antibodies in disease pathogenesis and its importance in the diagnosis of rheumatoid arthritis.