Interferons: biological and clinical effects.

Interferons play a key role in the immune system as biological response modifiers. Interferons alpha, beta, and gamma have been characterized, their nucleotide sequences defined, and the proteins produced by recombinant DNA technology. The myriad actions of interferons include enhancement of natural killer cell activity and antigen expression, induction of varied proteins, activation of macrophages, and antiviral, antiproliferative and antitumor effects. Clinical trials have demonstrated efficacy of interferons in some malignancies and ongoing studies are investigating results of combinations with other biological response modifiers and cytotoxic agents.