Effect of radioiodination on the binding of monoclonal antibody DF3 to breast carcinoma cells.
The murine monoclonal antibody (MAb) designated DF3 is an IgG1 prepared against a membrane enriched fraction of human breast carcinoma. MAb DF3 reacts with a family of large molecular weight glycoproteins expressed by 78% of breast cancer cells and 95% of epithelial ovarian cancer cells. Binding to the breast cancer cell line, MCF-7, of native MAb DF3 was compared to that of MAb DF3 exposed to different concentrations of Iodogen or Bolton-Hunter reagent. The amount of MAb DF3 required to obtain half-maximal binding (B1/2max) with MCF-7 extract for native MAb DF3 IgG was 180 ng, while the B1/2max for MAb DF3 IgG exposed to 1 and 10 micrograms Iodogen was 580 ng and 1800 mg, respectively. In contrast, the B1/2max for MAb DF3 IgG treated with Bolton-Hunter reagent was not different from that for native MAb DF3 IgG. Similar results were obtained with F(ab')2. Immunoreactive fractions for the 125I-labeled MAb DF3 were 0.13, 0.24 and 0.65 for IgG after exposure to 1 microgram Iodogen, 10 micrograms Iodogen and Bolton-Hunter, respectively. Immunoreactive fractions for F(ab')2 were 0.08, 0.08, and 0.53 for 1 and 10 micrograms Iodogen and Bolton-Hunter reagent, respectively. Association constants (Ka) were significantly higher for MAb DF3 IgG radioiodinated with Bolton-Hunter (3.97 +/- 0.38 x 10(8) M-1) than for IgG exposed to 1 microgram Iodogen (2.78 +/- 0.30 x 10(8) M-1) or 10 micrograms Iodogen (1.03 +/- 0.12 x 10(8) M-1). Similarly, the Ka ratio observed for the F(ab')2 radioiodinated with Bolton-Hunter reagent, 1 or 10 micrograms Iodogen was 22 to 3 to 1.(ABSTRACT TRUNCATED AT 250 WORDS)
Hayes
D F
DF
Laboratory of Clinical Pharmacology, Dana Farber Cancer Institute, Boston, Massachusetts.
Noska
M A
MA
Kufe
D W
DW
Zalutsky
M R
MR
D000911:Antibodies, Monoclonal / Q000276:immunology; D000951:Antigens, Neoplasm / Q000276:immunology*; D015295:Antigens, Tumor-Associated, Carbohydrate; D001666:Binding Sites, Antibody; D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D000939:Epitopes / Q000276:immunology; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D007553:Isotope Labeling / Q000379:methods; D011877:Radionuclide Imaging
D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D015295:Antigens, Tumor-Associated, Carbohydrate; D000939:Epitopes; D007457:Iodine Radioisotopes