MAJOR THERAPEUTIC USES OF INTERFERONS

Interferons are part of the body's natural defence system. They have shown in vitro and vivo to possess antiviral, antitumour and immunoregulatory properties. There are two types of interferon, type I and type II. Type I interferons comprise interferon-alpha (IFN alpha) and interferon-beta (IFN beta). Type II interferon is comprised solely of interferon-gamma (IFN gamma). Each type has distinctive genetic derivation, primary producing cells, and properties. IFN alpha is the most widely used interferon, and is produced commercially both by recombinant DNA technology and from stimulated leucocyte and lymphoblastoid cells. IFN beta is also available as a recombinant product and as a naturally produced product from human fibroblasts. IFN gamma is available as a recombinant product. The different types of interferons cannot be used interchangeably to obtain the same results. For instance, IFN gamma has been shown to aggravate multiple sclerosis, whereas IFN beta has a significant ameliorating effect. This article reviews the therapeutic use of interferons in: (a) viral infections, including condylomata acuminata, viral hepatitis and human immunodeficiency virus infection; (b) neoplastic disorders, including hairy cell leukaemia, multiple myeloma, AIDS-related Kaposi's sarcoma, cervical neoplasia, basal cell carcinoma, squamous cell carcinoma, melanoma, renal cell carcinoma, carcinoid tumours, cutaneous T cell lymphoma and non-Hodgkin's lymphoma; (c) myeloproliferative disorders, including chronic myelogenous leukaemia and polycythaemia vera; (d) rheumatoid disorders, including rheumatoid arthritis and systemic sclerosis; (e) other disorders, including multiple sclerosis, chronic granulomatous disease and cryoglobulinaemia. Many other diseases could have been included, but those mentioned have received the greatest amount of investigation and attention. The potential adverse effects of interferons are discussed. There is little doubt that the full therapeutic role of interferons has yet to be fully realized, either as single agents or in combination with other cytokines or drugs.