Interferons and Their Clinical Value

Interferons were discovered from their antiviral effects. It is now known that they are the products of families of genes found in many vertebrate species and that they bind to cell surfaces and produce a range of effects, varying from an antiviral state to increased expression of tissue transplantation antigens, decreased cell division, and modified im-mune responses, among others. Interferons are induced by exposure to viruses and double-stranded RNA, and one class, gamma interferon, is a lymphokine produced after a mito-genic or antigenic stimulus. The genes for human alpha, beta, and gamma interferons have been cloned and sequenced, and some have been expressed. When given parenterally to humans, interferons cause signs and symptoms such as fever, tachycardia, and malaise, and they may well be responsible for symptoms of this sort in viral infections. Prepara-tions of natural and recombinant alpha interferon have been shown to be active in pro-phylaxis and treatment of certain viral infections. In 1957 there was in the literature only one paper, by Isaacs and Lindenmann [I], on the subject of in-terferon (IFN), and reviewing the topic would have been easy. Four volumes are now needed to summa-rize recent work on IFN [2], so a short summary can no longer be comprehensive. I shall therefore out-line certain aspects of the basic biology of IFNs as we now understand them- what they are, what they ordinarily do, how they are related to diseases- and then indicate how we might exploit this knowledge. I do this because I believe that good clinical science means relating good biology- an understanding of living things- to the care of patients. We shall dis-cover that many IFNs are now known and that they do many different things. I shall have to omit a great deal, in particular, the relationship between IFN and "the immune system and the use of IFN inducers. The remainder, however, is still a fascinating story. Beginnings Isaacs first studied virus interference in a system using the cells of the chick embryo and live or Receivedfor publication February 4, 1986,and in revised for