Monoclonal Antibodies to Gelonin: Production and Characterization

BALB/c mice were immunized with gelonin, a 30 kD 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 10(9) M-1 and 10(10) M-1, respectively, as determined by a solid-phase EIA using the avidin-biotin system.