[Interferon].

Twenty five years ago Isaas and Lindenmann discovered that virus-infected cells may release a protein capable of reacting with normal cells and render them resistant to infection by a variety of viruses. That protein, a major mediator of viral interference was called interferon. Three main types of interferon have been identified and originally designated as fibroblast, leukocyte and immune interferon. According to the newly adopted nomenclature (as defined by the International Committee on Interfern Nomenclature) these interferons are now called beta, alpha and gamma interferon, respectively. The use of interferon as a therapeutic agent for tumor-bearing patients has gained considerable interest after reports demonstrated potent enhancing effects of interferon on the immunologic system. Thus, besides its direct effect on tumor cell multiplication, interferon may influence the host-tumor relationship by activating cells with potential antitumor activity such as natural-killer (NK) cells, killer (K) cells or macrophages. Interferon can also modify the metabolism of molecules involved in immunologic functions, such as antigen receptors, histocompatibility antigens or receptors for Fc fragment of immunologlobulins. Systematic clinical trials with interferon have been greatly expanded over the last three or four years. At this time the data support a cautious optimism for the therapeutic value of interferon in both viral and neoplastic diseases.