interferon

Interferons (IFNs) are proteins made and released by host cells in response to the presence of pathogens —such as viruses, bacteria, or parasites - or tumor cells. They allow for communication between cells to trigger the protective defenses of the immune system that eradicate pathogens or tumors. Based on the type of receptor through which they signal, human interferons have been classified into two major types:

1. Interferon type I: All type I IFNs bind to a specific cell surface receptor complex known as the IFN-α receptor (IFNAR) that consists of IFNAR1 and IFNAR2 chains. The type I interferons present in humans are IFN-α, IFN-β and IFN-ω.
2. Interferon type II: Binds to IFNGR that consists of IFNGR1 and IFNGR2 chains. In humans this is IFN-γ.