Anti-CCP antibodies play what role in autoimmune arthritis diagnosis?

• A. Anti-CCP antibodies are non-specific markers of autoimmune disease.
• B. Anti-CCP antibodies target citrullinated peptides and are highly specific for rheumatoid arthritis.
• C. Anti-CCP antibodies indicate infection with citrullinated proteins.
• D. Anti-CCP antibodies are useful for diagnosing all autoimmune diseases.

Answer: (D)

Anti-CCP antibodies are antibodies against citrullinated peptides, and they are used in diagnosing rheumatoid arthritis because they are highly specific for RA. Citrullination is a modification of protein arginine residues that occurs during inflammation, creating new antigenic targets. In RA, the immune system often generates antibodies to these citrullinated targets, so a positive anti-CCP test strongly supports RA and can be present early in the disease. They are not general markers of autoimmune disease, they do not indicate infection, and they do not diagnose all autoimmune conditions. In practice, anti-CCP testing complements other findings (like rheumatoid factor and clinical assessment) to improve diagnostic accuracy and can also provide some prognostic information about disease course.