CD25brightCD4+ T cells are enriched in the joint of patients with rheumatic diseases and are decreased in peripheral blood. (a) Representative fluorescence-activated cell sorting plots of paired peripheral blood (PB) mononuclear cells and synovial fluid (SF) mononuclear cells from one patient with psoriatic arthritis (PsA). Numbers within the gates represent the percentage of CD25brightCD4+ T cells of all CD4+ T cells. (b) Frequency of CD25brightCD4+ T cells in synovial fluid of patients with PsA, spondyloarthopathies (SpA), juvenile idiopathic arthritis (JIA) and rheumatoid arthritis (RA). Each triangle represents one individual. (c) The frequencies of CD25brightCD4+ T cells in peripheral blood were compared between healthy subjects and rheumatic patients. Significant differences between patient group and healthy subjects are indicated with asterisks: *** P < 0.0001; ** P = 0.001; * P = 0.02. Note that the scale is different from that in (b). (d) Relative increase of CD25brightCD4+ T cells in synovial fluid in comparison with that in peripheral blood (fold increase) analyzed in all patients from whom paired synovial fluid and peripheral blood samples had been obtained. na, not applicable.