This test detects the presence of anti CCP antibodies in the serum. Anti-citrullinated protein/peptide antibodies (ACPAs) areautoantibodies (antibodies directed against one or more of the individual’s own proteins) frequently detected in rheumatoid arthritispatients. Recently, these antibodies have turned up as powerful biomarkers, which are accepted as a major diagnostic tool indiagnosing rheumatoid arthritis (RA) already in a very early stage of disease.