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 . Sera of 22, 11, and 12 of these patients with RA, PsA, and OA, respectively, were similarly stored. IgG anti-CCP and IgA-RF were detected by enzyme-linked immunosorbent assay. Erythrocyte sedimentation rate and C-reactive protein levels were used as measures of disease activity.


RESULTS
Mean levels of synovial fluid anti-CCP and IgA-RF were significantly increased in RA joint effusions compared with PsA and OA (anti-CCP: 150 +/- 134, 34 +/- 29, and 24 +/- 26 units, respectively [P < 0.003]; IgA-RF: 76 +/- 77, 15.7 +/- 10, and 18 +/- 20 units, respectively). No significant difference was noted between OA and PsA. A significant correlation was found between synovial fluid anti-CCP and serum anti-CCP and IgA-RF. In patients with RA, a significant correlation was found between synovial fluid WBC counts and IgA-RF (P = 0.03) and serum IgA-RF (P = 0.008), but not between synovial fluid and serum anti-CCP levels. In RA patients, C-reactive protein correlated with serum IgA-RF.


CONCLUSIONS
Anti-CCP and IgA-RF were significantly increased in synovial fluid of RA in comparison with PsA and OA patients.
Caspi
Dan
D
Tel Aviv Sourasky Medical Center and the Sackler Faculty of Medicine, University of Tel Aviv, Tel Aviv 64239, Israel.
Anouk
Marina
M
Golan
Itzhak
I
Paran
Daphna
D
Kaufman
Ilana
I
Wigler
Irena
I
Levartovsky
David
D
Litinsky
Irena
I
Elkayam
Ori
O
D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D001168:Arthritis / Q000175:diagnosis* / Q000276:immunology* / Q000378:metabolism; D015535:Arthritis, Psoriatic / Q000175:diagnosis / Q000276:immunology / Q000378:metabolism; D001172:Arthritis, Rheumatoid / Q000175:diagnosis / Q000276:immunology / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000378:metabolism; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood / Q000276:immunology; D007719:Knee Joint / Q000276:immunology / Q000378:metabolism; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000175:diagnosis / Q000276:immunology / Q000378:metabolism; D010456:Peptides, Cyclic / Q000276:immunology*; D012217:Rheumatoid Factor / Q000097:blood / Q000276:immunology*; D012680:Sensitivity and Specificity; D013582:Synovial Fluid / Q000276:immunology* / Q000378:metabolism
D015415:Biomarkers; D007070:Immunoglobulin A; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide; D002097:C-Reactive Protein; D012217:Rheumatoid Factor