Differentiation of Th1 cells is triggered by interleukin 12 (IL-12) and characterized by high-level secretion of cytokines: Interferon gamma (IFN-γ), interleukin 2 (IL-2), and lymphotoxin, which recruits macrophages, B-lymphocytes, CD8+ T cells, natural killer (NK) cells, and neutrophils to the site of infection to impart protective Th1 immunity in both humans and mice [10]. Here, IFNG is linked to infection.