DN T-cells with T helper (Th)-like properties are capable of secreting cytokines such as interleukin (IL)-4, IL-17, interferon-γ (IFN-γ), and tumor necrosis factor (TNF)-α, thereby assuming a role analogous to that of CD4 Th cells in cases of infection and autoimmune disease (38–40). This evidence concerns the gene IL17A and infection.