[Interferons--biologic principles and clinical uses]

Interferons are components of the nonspecific defense system. Their most prominent biological roles are the antiviral, the antiproliferative, and the immunoregulatory activities. However, their primary functions within the organism remains to be determined. Three types of IFNs have been described so far (IFN alpha, IFN beta, IFN gamma). They possess similar but not necessarily identical biological activity. Interferons resemble peptide hormones and growth factors in that they bind to receptors on the cell surface, exert their activity through a postulated "second messenger" and are effective at picomolar concentrations. Interferons have been used as therapeutic agents in viral and malignant diseases with encouraging results in some patients. However, in only few instances interferon may become the standard therapeutic regimen. Since novel therapeutic approaches for cancer and viral disease are urgently needed, additional clinical trials with interferons seem to be justified. These have become feasible because sufficient amounts of pure interferon are available by novel production techniques based on modern biotechnology.