[A review of interferons: fifty years later (1957-2007)].

Initially identified as a defense mechanism against viral infections, in the last 50 years interferons have been defined a group of substances belonging to the cytokine family indispensable for the normal functioning of the immune system. Derived from their pleiotropic functions interferons were the first biological products used to treat several diseases. Their properties have progressively placed them as the first treatment choice for chronic infection with hepatitis B virus, hepatitis C virus, multiple sclerosis, some forms of leukemia, melanoma, etc. It has been noted however that the administration of supra physiological doses of interferons with therapeutic objectives, independently of its primary indication, has been associated with significant toxicity, including autoimmunity and induction of more than thirty different autoimmune diseases.