Monoclonal radiolabeling

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). 

Kobayashi, H., Sato, N., Saga, T., Nakamoto, Y., Ishimori, T., Toyama, S., Togashi, K., Konishi, J., and Brechbiel, M.W. (2000) Monoclonal antibody-dendrimer conjugates enable radiolabeling of antibody with markedly high specific activity with minimal loss of immunoreactivity. Eur. J. Nucl. Med. 27, 1334-1339. 

Liu, Y., and Wu, C. (1991) Radiolabeling monoclonal antibodies with metal chelates. Pure Appl. Cbem. 63, 427-463. 

Subramanian, R., and Meares, C.F. (1991) Bifunctional chelating agents for radiometal-labeled monoclonal antibodies. In Cancer Imaging with Radiolabeled Antibodies (D.M. Coldenberg, ed.), pp. 183-199. Kluwer, Boston, MA. 

Immunoassays employ monoclonal or polyclonal antibody preparations (Chapter 13) to detect and quantify the product (Box 7.1). The specificity of antibody-antigen interaction ensures good assay precision. The use of conjugated radiolabels (RIA) or enzymes (EIA) to allow detection of antigen-antibody binding renders such assays very sensitive. Furthermore, when compared with... 

Figure 13.5 Outline of the production strategy of CEA-SCAN. The antibody-producing hybridoma cell line was originally obtained by standard methods of hybridoma generation. Spleen-derived murine B-lymphocytes were fused with murine myeloma calls. The resulting stable hybridomas were screened for the production of anti-CEA monoclonals. The clone chosen produces an IgG anti-CEA antibody. Note that the finished product outlined above is not radiolabelled. The freeze-dried antibody preparation (which has a shelf life of 2 years at 2-8 °C) is reconstituted immediately prior to its medical use. The reconstituting solution contains 99mTc, and is formulated to facilitate direct conjugation of the radiolabel to the antibody fragment...

Preclinical studies should address the potential toxicity due to inappropriate release of the conjugated toxin. Preclinical toxicology of monoclonal antibodies may not require extensive animal studies but should be examined for cross-reactivity with antigenic epitopes present on normal cells in vitro and for the presence of human or rodent vimses. Early clinical trial should involve biodistribution studies with radiolabelled material. 

An allied application of radiolabelled anti-tumour monoclonal antibodies is that of diagnostic imaging (immunoscintigraphy). In this case, the radioisotope employed must be a y-emitter (such that the radioactivity can penetrate outward through the body for detection purposes). Although various radioisotopes of iodine have been evaluated, (technetium) is the one... 

Radiation therapy The use of high-energy radiation from x-rays, gamma rays, neutrons, and other sources to ktil cancer cells and shrink tumors. Radiation may come from a machine outside the body (external-beam radiation therapy), or it may come from radioactive material placed in the body in the area near cancer cells (internal radiation therapy, implant radiation, or brachytherapy). Systemic radiation therapy uses a radioactive substance, such as a radiolabeled monoclonal antibody, that circulates throughout the body. Also called radiotherapy, [nih]... 

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