Which statement is most specific for rheumatoid arthritis among commonly tested antibodies?

• A. Cyclic citrullinated peptide antibody
• B. Rheumatoid factor
• C. ANA
• D. Anti-Smith

Answer: (A)

Anti-CCP antibodies are highly specific for rheumatoid arthritis because they target citrullinated proteins that are closely associated with RA pathology. The presence of anti-CCP strongly supports RA and can even appear before joint symptoms, making it a powerful diagnostic clue. Rheumatoid factor is more sensitive but less specific, since it can be positive in other autoimmune diseases and in some healthy individuals. ANA is a broad marker of autoimmunity and isn’t specific to RA, while anti-Smith is highly specific for systemic lupus erythematosus rather than RA. So, the cyclic citrullinated peptide antibody is the best indicator of RA among these commonly tested antibodies.