CD4 and infection: Patients with chronic HCV infection showed significant increases in the frequencies of MDSCs and CD4+CD25+CD127- Tregs compared to healthy individuals (Fig 7E), and a positive correlation existed between the frequency of MDSCs and that of CD4+CD25+CD127- Tregs (Fig 7F), as well as positive correlation of HCV RNA level or HCVc protein level with the percentages of CD14+ MDSCs and CD4+CD25+CD127- Tregs in peripheral blood of chronic HCV patients was shown in S5 Fig.