Radiolabeled antibodies

Hnatowich, D.J. (1990) Antibody radiolabeling, problems and promises. Nucl. Med. Biol. 17, 49-55. 

The antibody reacts with both the radioactive and unlabelled hapten forming an antibody-radiolabelled antigen and antibody-unlabelled antigen complexes,... 

Antigens, haptens, and antibodies radiolabeled with or are commonly used as tracers in immunoassay. These nuclides can be introduced directly into functional groups normally present in proteins and other macromolecules or into suitable derivatives that can be synthesized by a variety of chemical procedures. The most widely used iodination methods have been direct chemical or enzymic substitution of hydrogen in tyrosine or related groups using chloramine-T or lactoperoxidase, respectively. These methods are described in separate chapters in this volume. 

Preparation and use of DTPA-coupled antitumor antibodies radiolabelled with yttrium-90. In Antibody-Mediated Delivery Sytems, Hnatowich, D.J., Snook, D., Rowlinson, G., Stewart, S., Epentos, A.A., Eds. Marcel Dekker, Inc. New York, 1988 353-374. 

Isothiocyanatobenzyl-EDTA is a chelating agent for the determination of the yield of antibody radiolabeling. ... 

Hnatowich D J, Childs R L, Lanteigne D, et al. (1983). The preparation of DTPA-coupled antibodies radiolabeled with metallic radionuclides An improved method. J. Immunol. Meth. 65 147-157. 

Immunoanalytical methods occupy an important position in bioanalytical chemistry. Chemical derivatization plays a fundamental role in this technique. Small analyte molecules (haptenes) are covalently bound to proteins to raise the antibody, which is the basis for their highly selective and sensitive assay. Various labeled derivatives of the analyte are then prepared for competitive binding on the antibody (radiolabeling, labeling for enzyme immunoassay, fluorescence immunoassay, fluorescence polarization immunoassay, and luminescence immunoassay). These derivatization reactions are carried out by the... 

The first series of metallo-carbonyl protein labeling reagents was designed from the popular Bolton-Hunter radio-iodination reagent 48 intended for antibody radiolabeling [85]. 

Radiotracers have also been used extensively for the quantitative rnicrodeterrnination of blood semm levels of hormones (qv), proteins, neurotransmitters, and other physiologically important compounds. Radioimmunoassay, which involves the competition of a known quantity of radiolabeled tracer, usually I or H, with the unknown quantity of semm component for binding to a specific antibody that has been raised against the component to be deterrnined, is used in the rnicro deterrnination of physiologically active materials in biological samples (see Immunoassay). 

Begent, R. H. J., Green, A. J., Bagshawe, K. D., Jones, B. E., Keep, P. A., Searle, F., Jewkes, R. F., Barrat, G. M., and Ryman, B. E. (1982). Liposomally entrapped second antibody improves tumor imaging with radiolabelled (first) antitumor anti-body. Lancet, 2, 739-742. 

A monoclonal antibody-based ELISA has been utilized to determine ceftiofur levels in milk. The authors noted that matrix interference occurred, but a 1 100 dilution lowered the interference, and a 1 1000 dilution eliminated the matrix interference. Because of the high dilution, samples could not be measured below l.Opgkg The assay measured ceftiofur, its major metabolite desfuroylceftiofur, and ceftiofur protein conjugates and has been utilized to measure residues in milk from cows treated with therapeutic doses of the drug. The results from the incurred residue correlated well with a previous study using radiolabeled ceftiofur, confirming the detection of a metabolite that was not detected by HPLC. 

Antibody. Rat monoclonal antibody 34A was purified from nu/nu mouse ascites fluid as described (79). The 34A was radiolabeled with 125I using IDO-GEN (Pierce, Rockford, IL) method to a specific activity of 2 to 4 x 105 cpm/pg, and conjugated with NGPE as previously described (7). 

Fig. 7. General scheme for radiolabeling antibodies with rhenium using N2S2-ligand (N3S-ligand)...

Figure 20.18 The bifunctional chelating reagent DTPA may be used to modify amine groups on antibody molecules, forming amide bond linkages. Indium-111 then may be complexed to the chelator group to create a radiolabeled-targeting reagent.

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