Interleukin 13 in synovial fluid and serum of patients with psoriatic arthritis

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Ann Rheum Dis 2002 Feb;61(2):174-6

Interleukin 13 in synovial fluid and serum of patients with psoriatic

arthritis.

Spadaro A, Rinaldi T, Riccieri V, Valesini G, Taccari E.

Department of Medical Therapy, Rheumatology Unit, University of Rome La

Sapienza, Italy. a.spadaro.reuma@...

OBJECTIVES: To compare the pattern of interleukin (IL) 13 production in

synovial fluid (SF) and serum of patients with psoriatic arthritis (PsA)

with that in patients with rheumatoid arthritis (RA) and osteoarthritis

(OA), investigating its relation to the proinflammatory cytokine IL12.

METHODS: SF and serum IL13 levels were determined in 35 patients with

PsA, 36 with RA, and 15 with OA. The main clinical and laboratory

variables, including number of painful and/or swollen joints, Ritchie

index, morning stiffness, erythrocyte sedimentation rate, level of C

reactive protein, level of rheumatoid factor, and SF analysis, were also

evaluated. RESULTS: SF IL13 levels were significantly higher in patients

with PsA (p<0.02) or RA (p<0.012) than in patients with OA, with no

significant difference between the former two. SF IL12 levels were

significantly higher in patients with PsA (p<0.023) than in those with

OA. Serum IL13 (p<0.0001) and IL12 (p<0.02) levels were lower in

patients with PsA than in those affected by RA. Only patients with PsA

had higher IL13 levels in SF than in serum (p<0.002). The IL13 SF/serum

ratio was higher in the PsA group than in the group with RA (p<0.005) or

OA (p<0.026). SF IL13 levels correlated with serum IL13 levels

(p<0.0001) in RA and with SF IL12 levels (p<0.03) in PsA. CONCLUSIONS:

In PsA, there appears to be localised production of IL13, in balance

with IL12, in the inflamed joints. The distinct IL13 secretion profiles

in PsA, RA, and OA may be related to the clinical pictures, reflecting

the different pathogenic mechanisms involved in inflammatory and

degenerative joint diseases.