Synovial fluid levels of anti-cyclic citrullinated peptide antibodies and IgA rheumatoid factor in rheumatoid arthritis, psoriatic arthritis, and osteoarthritis.

Objective: To assess the levels of anti-cyclic citrullinated peptide (anti-CCP) and IgA rheumatoid factor (IgA-RF) in synovial fluids of patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA), and osteoarthritis (OA).

Methods: Knee effusions of 29 patients with RA (23 women, 6 men; mean +/- SD age 60 +/- 15 years), 20 with PsA (6 women, 14 men; mean age 51 +/- 12 years), and 19 with OA (9 women, 10 men; mean age 73 +/- 11.8 years) were aspirated, tested for white blood cell (WBC) counts, centrifuged, and stored at -20 degrees .