Antigenic characteristics of glycosylated natural and unglycosylated recombinant human gamma-interferon.

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