What is the difference between ACPA and anti CCP antibodies?
Researchers have identified RA-related autoantibodies directed against specific citrullinated peptides in the synovium, joint fluid, and other target tissues of patients with RA. The term ACPAs was developed as an umbrella term for this collection of antibodies directed against specific citrullinated peptides. Several potentially important joint-targeted citrullinated autoantigens in RA have been discovered including fibrinogen, α-enolase, type II collagen, and vimentin. The exact citrullinated proteins included in the commercially available anti-CCP test, however, are proprietary. As such, it is uncertain how much overlap exists between these assays and the joint-specific targets identified through research. ELISA-based assays using specific joint-targeted peptides have been investigated, including mutated citrullinated vimentin (anti-MCV antibody). In regards to diagnosis, research has not shown a clear role for the testing of individual ACPA assays over commercially available anti-CCP tests. Multiplex assays are currently being investigated that can allow for simultaneous testing of numerous ACPAs. Further investigation is needed to determine if such platforms may improve the sensitivity for detection of ACPAs in RA patients who are seronegative for RF and anti-CCP.