CCL21 and juvenile idiopathic arthritis: Concentrations of CCL21 were significantly higher in SF (median 1769.5 pg/ml, range 110–25,556 pg/l) than in paired sera from patients with JIA (median 268 pg/ml, range 57.6–5146.9 pg/ml, P < 0.0001; Wilcoxon test; Fig. 4a).