TNF and HIV infectious disease: Th17 cells mediate protection by producing IL-17A, IL-17F, IL-21, and IL-22 (16), while Th1 cells produce IL-1β, IL-2, IL-12, tumor necrosis factor (TNF)-α, and IFN-γ (17), but both are thought to be highly susceptible to HIV infection, especially in their activated state (18, 19).