Under normal physiological conditions, PD-1 which acts as immune checkpoint could interact with its two ligands, PD-L1 and PD-L2, and plays a very important part in lowering the immune system though suppression of T-cells function, upregulating regulatory T cells (Treg), which in turn reduces autoimmunity and promotes self-tolerance [23,24]. This evidence concerns the gene CD274 and Autoimmunity.