True about interferons is ?

Interferon (IFNs ) are a group of signaling proteins made and released by host cells in response to the presence of several viruses.  In a typical scenario, a virus-infected cell will release interferons causing nearby cells to heighten their anti-viral defenses.  IFNs belong to the large class of proteins known as cytokines, molecules used for communication between cells to trigger the protective defenses of the immune system that help eradicate pathogens.  Interferons are named for their ability to "interfere" with viral replication by protecting cells from virus infections.  IFNs also have various other functions: they activate immune cells, such as natural killer  cells and macrophages; they increase host defenses by up-regulating antigen presentation by virtue of increasing the expression of major histocompatibility complex (MHC) antigens.