Interferon standards: a memorandum.

The progress that has been made in the production of human interferons has led to clinical trials that suggest significant antiviral and antitumor effects. The growing possibilities of clinical usefulness and the greater appreciation of the complexity of the nature and actions of interferon, as well as its possible, varied biological roles, are factors that dictate the need for international interferon standards. This memorandum includes recommendations regarding characterization and use of interferon standards; definition of unitage; calibration of assays and reporting requirements; use of cells, viruses, and reagents in interferon assays; and description of a reference interferon bioassay.