Type II IFN is produced both in the early stages of infection by NK cells or macrophages (34, 35) and at later stages by activated T lymphocytes (36), either via receptor-mediated stimulation (through T or NK cell receptors) or in response to early produced cytokines, such as IL-12, IL-18, and IFN-α/β (35). This evidence concerns the gene IL18 and infection.