The three types of interferon are glycoproteins released from virus-infected cells or those exposed to stimuli which mimic virus infection. They not only inhibit the growth of viruses but also inhibit the growth and reduplication of cells. This is the basis for their investigation as a means of treating cancer.

Interferon alfa has some antitumour effect on certain solid tumours and lymphomas. It is also used to treat HEPATITIS B and C (chronic variety). Various side-effects include suppression of MYELOBLAST production. Interferon beta is used to treat patients with relapsing, remitting MULTIPLE SCLEROSIS (MS), and interferon beta–16 is licensed for use in patients with the secondary progressive type of this disorder.