The frequency of regulatory T (Treg) cells and T helper type 17 (Th17) cells as well as Treg : Th17 ratio in patients treated with pegylated interferon-α2a (IFN-α2a) and ribavirin during the course of therapy. (a) The frequency of Treg cells was observed from baseline to the 48 weeks in rapid virological response (RVR), early virological response (EVR) and non-response (NR) patients. (b) The frequency of Th17 cells was observed from baseline to the 48 weeks in RVR, EVR and NR patients. (c) The ratio of Treg cells to Th17 cells was observed from baseline to the 48 weeks in RVR, EVR and NR patients. Error bars illustrate the standard errors. #P < 0·05, ##P < 0·01, ###P < 0·001 refers to the statistical differences among RVR, EVR and NR at each time-point.