Clusters 2 and 15 were clearly separated from other clusters by high Ki67 expression, denoting cycling Tregs, which were present across all sites (cluster 2: 2.82 ± 0.28% of HC, 4.73 ± 0.74% of JIA PB, 1.80 ± 0.51% of JIA SF Tregs; cluster 15: 8.74 ± 0.91% of HC, 5.40 ± 0.61% of JIA PB, 4.38 ± 0.69% of JIA SF Tregs, Fig. 5B and C). This evidence concerns the gene MKI67 and juvenile idiopathic arthritis.