Fig. 3

Frequencies of IL-10 producing regulatory B (B10) cells in juvenile idiopathic arthritis (JIA) patients and controls. a Representative intracellular IL-10 staining in B cells in peripheral blood (PB) of one JIA patient with/without stimulation of CpG + CD40L for 48 h and phorbol 12-myristate 13-acetate+ionomycin+brefeldin A (PIB) for the last 6 h (right). Few B cells produced IL-10 when cultured with PBS only (left). Isotype controls were used to set up the negative population (lower). b Comparison of B10 cells frequencies in PB of different groups of JIA patients, synovial fluid (SF) of JIA patients, and PB of controls (left). c Comparison of B10 cells frequencies in active and inactive patients. BFA, brefeldin A; CD40L, CD40 ligand; Iso, isotype; PBMC, peripheral blood mononuclear cells; PBS, phosphate-buffered saline; PIB, phorbol 12-myristate 13-acetate+ionomycin+brefeldin A; poly-JIA, polyarticular juvenile idiopathic arthritis. *p < 0.05, **p < 0.01,***p < 0.001