Higher levels of T cell activation and lower levels of Tregs in HIV/HCV co-infected subjects when compared to HCV mono-infected subjects. (A) CD3+CD8+CD38+ percentages (%) of lymphocytes, mean fluorescent intensity (MFI) of CD38 on CD3+CD8+ T cells, and CD3+CD8+HLA-DR+ % of lymphocytes in HCV mono-infected and HIV/HCV co-infected subjects; (B) MFI of CD38 on CD3+CD8+ T cells in one representative HCV mono-infected subject [subject 003, MFI CD38 on CD3+CD8+ T cells = 156 (red line)] and one representative HIV/HCV co-infected subject [subject 054, MFI of CD38 on CD3+CD8+ T cells = 360 (blue line)] are shown; (C) Tregs % of lymphocytes in HCV mono-infected and HIV/HCV co-infected subjects; (D) MFI of CD160 on CD3+CD8+ T cells, in HCV mono-infected and HIV/HCV co-infected subjects. Data in panels (A), (C) and (D) are shown as inter-quartile box plots with median and outliers for each group, and significant (<0.1) P values.