Production of cytokines and proliferation of responder cells in patients with psoriatic arthritis (PsA), spondyloarthopathies (SpA), juvenile idiopathic arthritis (JIA) and rheumatoid arthritis (RA) are shown. Changes in cytokine and proliferation levels after coculture with CD25brightCD4+ T cells are shown in Fig. 5. bdl, below detection limit; IFN, interferon; IL, interleukin; na, not analyzed; TNF, tumor necrosis factor. aEnzyme-linked immunosorbent assay; detection limit is 50 pg/ml; 20,000 cells per well in coculture. bCytometric bead array; detection limit is 3 pg/ml; 5000 cells per well in coculture.