An immunoradiometric assay of serum interferon using a monoclonal antibody.

An immunoradiometric assay for human interferon-alpha (HuIFN-alpha) has been adapted for the assay of low concentrations of HuIFN-alpha in human serum. The sensitivity of the assay is 5 to 10 IU/ml and the coefficient of variation less than 10%. The assay was shown to compare well with a biological (antiviral) assay in the measurement of serum interferon following intramuscular injection of HuIFN-alpha in nine volunteers. Serum interferon was also measured in the serum from 250 normal human donors. Two donors appeared to have detectable levels of HuIFN-alpha.