Interferon therapy in primary care.

Interferons are proteins produced by human blood cells in response to stimulation (viral infection). The natural roles of interferons are host defense and modulation of the immune system. Therapeutic uses are based on these roles. Interferon-alpha has been widely used for malignancies, skin conditions, viral infections, and myeloproliferative disorders. Interferon-beta is a standard treatment for relapsing multiple sclerosis. Interferon-gamma therapy is currently used for chronic granulomatous disease and skin lesions (human papilloma virus related and keloids), but further research is ongoing. Side effects of interferon therapy are common and limit utility. Flulike symptoms are reported by more than 75% and depression by 10-40% of interferon users. Severe adverse effects are less common but may be life threatening, including autoimmune diseases, thrombotic-thrombocytopenic purpura, and acute renal failure. Limited use of interferon therapy during pregnancy has been described, with successful maternal and neonatal outcomes. Use of interferon therapy during early pregnancy is not an indication for termination.