IFNG and HIV-1 infection: It has previously been documented that secretion of T-helper type 1 (Th 1) cytokines, such as interleukin (IL-2) and interferon-gamma (IFN-γ), is reduced during HIV-1 infection, although production of T helper 2 (Th 2) cytokines, such as IL-4, IL-10, IL-1β, IL-6, tumor necrosis factor (TNF-α), and TGF-β1, is elevated [19,20].