Interferon alpha-B, also known as IFNA8, belongs to the alpha/beta interferon family. Interferons are proteins made and released by host cells in response to the presence of pathogens such as viruses, bacteria, parasites, or tumor cells. Interferon stimulates the production of two enzymes: a protein kinase and an oligoadenylate synthetase. They also allow for communication between cells to trigger the protective defenses of the immune system that eradicate pathogens or tumors. Interferons also activate immune cells, such as natural killer cells and macrophages. They increase recognition of infection or tumor cells by up-regulating antigen presentation to T lymphocytes. They also increase the ability of uninfected host cells to resist new infections by virus. Certain symptoms, such as aching muscles and fever, are related to the production of IFNs during infection. Produced by macrophages, IFN-alpha has antiviral activities.