Production of a monoclonal antibody to human interferon-α (IFN-α) and its use to identify IFN-α-producing cells in virus infection in vivo

Abstract

A monoclonal antibody to human interferon-α (IFN-α) was produced using affinity-purified IFN-α, that reacted with recombinant human IFN-α2, but not with IFN-α1, IFN-αM1 or IFN-β. Indirect immunofluorescence using this monoclonal (designated 6C3) and anti-IFN-α polyclonal antibodies identified cells expressing IFN-α. After Sendai virus induction of normal human buffycoat cells the proportion of monocytes and lymphocytes expressing IFN-α rose progressively from 0% to 50% and 34% respectively, preceding peak IFN-α titres in the culture supernatants. Around 80–90% of polymorphs were IFN-α-positive using both antisera, with or without IFN induction, although very little IFN bioactivity was released to the supernatant of polymorph cultures after IFN induction. Sections of hepatitis B virus infected human liver tissue showed foci of IFN-α-positive infiltrating mononuclear cells and (to a lesser extent) fibroblasts in patients who had active cirrhosis and evidence of virus replication. These findings suggest that polymorphs constitutively express IFN-α2 related antigenic activity, whose biological activity is at present unknown; and demonstrates the identification of IFN-α-expressing cells in sections of tissue undergoing natural virus infection.