CONCISE REPORTS T cell derived cytokines in psoriatic arthritis synovial fluids

Objective—The aim of this study was to investigate the concentrations of T cell derived cytokines in the synovial fluids (SFs) of patients with psoriatic arthritis (PsA) in comparison with rheumatoid arthritis (RA) and osteoarthritis (OA). Methods—Th1 type cytokines (interleukin 2 (IL2), tumour necrosis factor â (TNFâ), and interferon ã (INFã)) and Th2 type cytokines (IL4, IL10) were measured by means of enzyme linked immunosorbent assays. Results—IL2 was usually not detectable in any of the disease groups. TNFâ was found in 3 of 31 PsA SFs (mean (SEM) 11.1 (2.3) pg/ml) and in a significantly lower concentration than in 20 of the 40 RA SFs (42.2 (15.6) pg/ml; p < 0.002). INFã was measurable in 2 of 10 PsA and 6 of 16 RA SFs (p > 0.05). IL4 was present at low concentrations in 4 of 22 PsA SFs (0.41 (0.8) pg/ml), and in 15 of 20 RA SFs (0.63 (0.09) pg/ml; p < 0.01). IL10 was found in 4 of 27 PsA SFs (12.3 (0.9) pg/ml) and in 27 of 32 RA SFs (37.3 (4.9) pg/ml; p < 0.0001). In all OA SFs cytokine concentrations were below the limit of detection. Conclusion—The pattern of T cell derived cytokines in PsA SFs was similar to that of RA SFs. However, both the frequency and the concentrations of cytokines were lower in PsA SFs than in RA SFs, while OA SFs generally lacked any detectable T cell cytokines altogether. The presence of Th1 and Th2 cell derived cytokines in PsA SFs suggests the presence of activated T cells in the inflamed joint tissues and their participation in the immunoinflammatory events. (Ann Rheum Dis 1998;57:691–693) T cells are important cellular components in the development of inflammatory joint diseases such as rheumatoid arthritis (RA). 2 Psoriatic arthritis (PsA), an inflammatory seronegative disease of unknown aetiology, is also characterised by the infiltration of joints and involved skin by activated T cells. The synovial membranes of PsA and RA cannot be diVerentiated from each other by immunohistology. Activated T cells belong to two major subpopulations, which may be diVerentiated by their cytokine profiles: Th1 cells produce the proinflammatory cytokines interleukin 2 (IL2), tumour necrosis factor â (TNFâ), and interferon ã (INFã), while Th2 cells synthesise the anti-inflammatory cytokines IL4 and IL10. As the role or presence of T cell derived cytokines in PsA is still unknown, we investigated them and compared them with those in RA and osteoarthritis (OA).