Antigenic Characteristics of Glycosylated Natural and Unglycosylated Recombinant Human Gamma-Interferon

ABSTRACT Neutralizing polyclonal antibodies raised in rabbits against glycosylated natural human gamma-interferon (nIFN-γ) and unglycosylated recombinant IFN-γ (rIFN-γ) were tested for their ability to bind to several polypeptides spanning the entire amino acid sequence of the rIFN-γ molecule. Antibodies raised in four rabbits against rIFN-γ all bound efficiently to relatively large polypeptides whose sequences started from the amino-terminus, rIFN-γ 1–48, 1–59, 1–80, and the internal polypeptide IFN-γ 81–120. These antibodies bound poorly or not at all to the following polypeptides: IFN-γ 1–20, 24–59, 36–59, 87–96, 121–137, 121–146, 138–146. In contrast, antibodies raised in four rabbits against nIFN-γ in general bound less well to IFN-γ 1–48, 1–59, 1–80, and 81–120. In addition, all the other polypeptides cited above were recognized to some degree by anti-nIFN-γ antibodies. These results suggest that the oligosaccharide side-chains of nIFN-γ cover or perturb the structure of antigenic sites present in r...