HuIFN-gamma antiviral activity correlates with immunological reactivity in a double-monoclonal antibody radiometric assay.

Several lines of evidence have been obtained that correlate biological activity with reactivity in an immunoradiometric assay (IRMA) employing two different monoclonal antibodies. Antiviral activity and immunological reactivity decreased in parallel when freeze-dried human gamma-interferon (HuIFN-gamma) was heated for prolonged periods of time at elevated temperatures. Likewise, aqueous preparations of HuIFN-gamma inactivated by acid pH or heat responded similarly in the biological assay and IRMA. These results indicate that the monoclonal antibodies used in this commercially available IRMA are specific for the epitopes on biologically activity HuIFN-gamma.