Increased sensitivity of an enzyme immunoassay for human interferon alpha 1 using a mixture of three monoclonal antibodies

A sensitive sandwich ELISA for the quantification of human interferon (IFN)-alpha 1 was designed. The assay employed IFN-alpha 1- specific polyclonal antibody for coating and monoclonal antibodies (mAbs) to IFN-alpha 1 as a second antibody. A major increase in sensitivity of the assay could be achieved, when polyclonal antibody was combined with a mixture of three mAbs binding to different regions of IFN-alpha 1, compared to the combination of a polyclonal antibody with a single mAb. The sensitivity of the established ELISA was close to that of an antiviral IFN-bioassay. The ELISA did not cross-react with IFN-alpha 2, beta, tau or omega. The immunoassay allowed to estimate the content of IFN-alpha 1 in leukocyte IFN-alpha to about 25-50% or to 2-6% in Namalwa IFN-alpha, respectively.