IFNG and infection: At the baseline level, co-infected with HCV can decrease the cytokine levels produced by both Th1 and Th2 cells comparing with HIV mono-infection except IL-10; HIV mono-infection had the highest Th1 immune responses by secreting IFN-γ compared with other groups; Th2 cytokine levels were lower than Th1, demonstrated a profile dominated by Th1 cytokines before HAART.