Interferon type II

A sole member makes up the type II interferons (IFNs) that is called IFN-γ (gamma). Mature IFN-γ is an anti-parallel homodimer, which binds to the IFN-γ receptor (IFNGR) complex to elicit a signal within its target cell. IFNGR is made up of two subunits each of molecules designated IFNGR1 and IFNGR2. A sole member makes up the type II interferons (IFNs) that is called IFN-γ (gamma). Mature IFN-γ is an anti-parallel homodimer, which binds to the IFN-γ receptor (IFNGR) complex to elicit a signal within its target cell. IFNGR is made up of two subunits each of molecules designated IFNGR1 and IFNGR2. Interferon- γ is a cytokine that has an important role in adaptative and innate immunity. Thus, it helps fight against some bacteria and inhibit viral replication. Moreover, this cytokine stimulates and modulate immune system. It belongs to Type II interferon and it is the only one in this class. It is serologically different from interferon type 1 as well as binds to different receptors and is encoded by a separate chromosomal locus. Interferon-γ is secreted by a huge number of cells as well as is involved in the regulation of others. As an immune response, this homodimer is released by natural killer T lymphocytes (NK). When the antigen-specific immunity complex develops, it is produced by CD4 Th1 and CD8 cytotoxic T lymphocyte (CTL) effector T cell. Furthermore, non-cytotoxic innate lymphoid cells (ILC) as well as mucosal epithelial cells, macrophages and B cells secrete IFN-γ. The presence of IFN-γ in T helper cells makes that undifferentiated CD4+ cells (Th0 cells) to differentiated into Th1 cells. Therefore, there is a positive feedback loop which suppress Th2 cell differentiation.The defense against an infection is led by NK cells when they secrete the interferon, whereas the adaptative immune response is directed by mainly T lymphocytes with interferon-gamma. APCs release a sort of cytokines that control the production of IFN-gamma. This cytokines are IL-12 and IL-18 which serve to connect the infection with IFN-gamma production in the innate immunity response. Once macrophages recognize pathogens, it causes the secretion of IL-12 and chemokines. These chemokines attract NK cells to the inflammation, and IL-12 bring about IFN-gamma synthesis in these cells. Apart from macrophages and NK cells, the production of the interferon-gamma by T cells is controlled by these two interleukin.