Quantitative determination of human leukocyte interferon by microfluorometric immunoassay with FITC-labeled...

The possibility of quantitative determination of human leukocyte interferon using FITC-labeled anti-interferon antibody was studied. Anti-interferon immunoglobulin of high specific activity was obtained as a result of long-term immunization of a donkey with human leukocyte interferon preparation and subsequent fractionation and immunoadsorption steps. This immunoglobulin was labeled with FITC and then used for titration of human leukocyte interferon by the fluorescence inhibition immunoassay. The titres of different preparations of human leukocyte interferon in the immunoassay were comparable with the titres of the same preparations detected by the inhibition of a cytopathic effect of VSV.