Anti-cyclic citrullinated peptide antibody determination in synovial fluid of psoriatic arthritis.
OBJECTIVE
To assess the role of anti-CCP antibodies in synovial fluid (SF) of psoriatic arthritis (PsA) patients by analysing their association with different clinical patterns of the disease.


METHODS
Seventy-five patients with a knee-joint effusion were studied, including 31 PsA patients, 29 rheumatoid arthritis (RA) and 15 osteoarthritis (OA) patients. SF and paired serum samples were stored at -70 degrees C until IgG anti-CCP and total IgG determination. The pattern of PsA articular involvement was defined as mono-, oligo-, polyarticular or axial.


RESULTS
Lower levels of IgG anti-CCP antibodies in SF (p < 0.01) and serum (p < 0.005) were found in PsA respect to RA patients without difference with OA. We found a higher SF/serum ratio for anti-CCP compared to the SF/serum ratio for total IgG in PsA (p < 0.0005) as well as in RA and OA. The correction of anti-CCP concentration in SF as IgG anti-CCP (unit) / total IgG revealed lower (p < 0.002) values in PsA patients with respect to RA patients. In PsA group, values of anti-CCP antibodies, SF/serum ratio of anti-CCP and anti-CCP/IgG above the cut-off were found in 5, 6 and 2 SF samples respectively. The presence or absence of anti-CCP antibodies did not discriminate a particular clinical subset.


CONCLUSIONS
In conclusion, strengthening the concept of local production of anti-CCP antibodies within the joint space, our results suggest that anti-CCP antibody detection in SF should take into account corrections such as total amount of corresponding immunoglobulin or SF/serum ratio. In our study, the presence or absence of anti-CCP antibodies did not discriminate a particular clinical subset, but further longitudinal studies are required to clarify the clinical role of anti-CCP in PsA.
Spadaro
A
A
Dipartimento di Clinica e Terapia Medica - Rheumatology Unit, Divisione di Reumatologia, Università di Roma La Sapienza, Azienda Policlinico Umberto I, Rome, Italy. a.spadaro.reuma@ virgilio.it
Riccieri
V
V
Scrivo
R
R
Alessandri
C
C
Valesini
G
G
D000293:Adolescent; D000328:Adult; D000368:Aged; D015535:Arthritis, Psoriatic / Q000276:immunology*; D001172:Arthritis, Rheumatoid / Q000276:immunology; D001323:Autoantibodies / Q000032:analysis* / Q000097:blood; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis / Q000097:blood; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000276:immunology; D010456:Peptides, Cyclic / Q000276:immunology*; D013582:Synovial Fluid / Q000276:immunology*
D001323:Autoantibodies; D007074:Immunoglobulin G; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide