Monoclonal Antibodies to Gelonin: Production and Characterization

Abstract

BALB/c mice were immunized with gelonin, a 30kD glycoprotein (type 1 RIP) from the seeds of Gelonium multiflorum. By polyethylene glycol-induced fusion of isolated spleen cells with the myeloma cell line NS-1, three different hybridomas were obtained. Two of them were found to secrete antibodies of the IgG₁ subclass, whereas the third cell line produced antibodies of the IgM type. The IgG₁-secreting cell lines were adapted to serum-free medium conditions, and the antibodies were isolated from the culture supernatant. The isolated antibodies recognize independent epitopes on the gelonin molecule. The toxicity of gelonin in reticulocyte lysates was not affected when the protein was incubated with the antibodies. The IgG₁s exhibit average affinity constants of about 10⁹ M^-1 and 10¹⁰ M^-1, respectively, as determined by a solid-phase EIA using the avidin-biotin system.