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)