Antigenic structure of human interferon omega 1 (interferon alpha II1): comparison with other human interferons

Recombinant human interferon (IFN) omega 1 (IFN-alpha II1) was compared with other human IFNs with regard to antigenic structure, using polyclonal and monoclonal antibodies. Antisera to recombinant IFN-alpha 1 or IFN-alpha 2c cross-neutralized the antiviral activity of other species of IFN-alpha, but not that of IFN-omega 1. Antisera to IFN-beta or IFN-gamma likewise had no effect on IFN-omega 1. Conversely, antiserum to IFN-omega 1 did not neutralize any of the other IFNs examined (IFN-alpha 1, -alpha 2c, -alpha 10, -alpha B, -alpha F, -beta, -gamma). None of four monoclonal antibodies to IFN-alpha, including a broad-spectrum antibody that neutralized all five recombinant species of IFN-alpha tested, had any effect on the biological activity of IFN-omega 1. Various immunoassays for IFN-alpha did not recognize IFN-omega 1. In immunoprecipitation experiments, radiolabelled IFN-alpha 2c was not precipitated by antiserum to IFN-omega 1. In contrast, antisera to human leukocyte IFN or 'lymphoblastoid' IFN did neutralize IFN-omega 1, although with titres significantly lower than those towards the immunogen or recombinant species of IFN-alpha. In conclusion, human IFN-omega 1 is antigenically different from human IFN-alpha, IFN-beta or IFN-gamma, but is a component of 'natural' mixtures of IFN species produced by virus-induced leukocytes or Burkitt's lymphoma cells.