Expansion of myeloid-derived suppressor cells from peripheral blood decreases after 4-week antiviral treatment in patients with chronic hepatitis C.

Myeloid-derived suppressor cells (MDSCs) are one of the most important regulators of anti-tumor T-cell responses in cancers. This study aimed to investigate MDSCs in the peripheral blood of patients with chronic hepatitis C (CHC) before and after 4-week treatment with pegylated interferon (PEG-IFN) and ribavirin, and to evaluate their correlation with CD4(+)CD25(high) regulatory T cells (Tregs) and clinical parameters. A total of 80 patients with CHC were enrolled into this study, 37 of whom were treated with PEG-IFN and ribavirin. Compared with healthy controls (0.462% [range 0.257%-0.634%]), the proportion of MDSCs in the peripheral blood of 80 CHC patients (0.601% [range 0.333%-1.027%]) increased significantly before therapy (P=0.011). For 37 HCV patients, the proportion of circulating MDSCs (0 w: 0.597% [range 0.296%-1.021%], 4 w: 0.126% [0.066%-0.239%], P<0.01) and Tregs (0 w: 2.467±0.927%, 4 w: 2.074±0.840%, P=0.047) decreased significantly after 4-week antiviral treatment. No significant correlation was found between MDSCs and Tregs. These findings suggest that MDSCs expand in the peripheral blood of CHC patients, but decrease after 4-week antiviral treatment.