Haufe S, Haug M, Schepp C et al. Arthritis Rheum 2011;63:3153–62.
In juvenile idiopathic arthritis (JIA), synovial fluid (SF) contains activated effector T cells that are presumed to contribute to inflammation, despite the presence of regulatory T cells (Tregs). These authors found that SF T cells were relatively resistant to Tregs, an observation that may help explain the failure of Tregs to control synovitis in JIA.
Regulatory T cells (Tregs) represent a key mechanism for the maintenance of T cell tolerance. Indeed, Tregs have been reported to be present in higher numbers in the synovial fluid (SF) of patients with the milder, often self-remitting form of juvenile idiopathic arthritis (JIA; oligoarticular JIA) than in more aggressive forms of the disease. Yet these cells are present in inflamed joints from multiple disease subtypes, raising the question of why inflammation persists. Does this represent a defect in synovial Tregs, or resistance of synovial T effector cells to control?