Immunoassay for the quantitation of human leukocyte interferon.

A sensitive nonradioactive immunoassay based on monoclonal antibodies was developed. A number of monoclonal hybridomas secreting antibodies against human leukocyte interferon (IFN alpha) were generated using mice immunized with purified lymphoblastoid IFN. Although the binding of antibody to IFN alpha was used as one criterium of selection, all antibodies found can neutralize its antiviral activity. A pair of antibodies binding to different regions of IFN alpha was identified. These were incorporated into sensitive sandwich assays of IFN alpha. A microtiter plate assay - using horse radish peroxidase as marker enzyme - is able to detect IFN alpha at a concentration of 30 IU/ml within 5 h. An overnight tube assay can detect approximately 30 pg IFN alpha 2 or 3 IU per ml solution. The 5-h ELISA (enzyme-linked immunosorbent assay) is well suited for the monitoring of the recovery of rIFN alpha from recombinant organism, during purification and refinement of the protein to a therapeutic drug.