Herein, we found a markedly decreased frequency of active Treg cells (CCR4+CD45RA−CD25+CD127low−CD4+CD8−CD3+) in both CKD and ESKD groups, whereas the percentage of total Treg (CD25+CD127lowCD4+CD8−CD3+) in ESKD group was statistically higher than CKD but of no difference compared to HC (Figures 3J,K). Here, CCR4 is linked to chronic kidney disease.