IL-18 is a multifunctional cytokine secreted mainly by monocytes/macrophages that has various biological functions, such as inducing IFN-γ production by Th1 cells, enhancing NK cell activity, and enhancing FasL-mediated cytotoxic effects, and has an important role in the immune response process, anti-infection, inflammatory response and autoimmune diseases (16, 17). This evidence concerns the gene FASLG and infection.