Radioactively Labeled mAbs

Another mode of action is the targeted delivery of a defined dose of radiation by a mAb, which is used almost exclusively in tumor therapy. One common radiation 

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Advances in generation of antibodies especially mAbs enabled the development of wide variety of the ELISA formats. For many applications, the ELISA replaced the older radioimmunoassay (RIA) method that is based on a detection of antibody-antigen reaction in solution using radioisotope. In the ELISA methods the radioactive label of an RIA is replaced by an enzyme conjugate. 

Fig. 1. Comparison ot human PR detected by photoaffinity labeling and immunoblotting. Intact T47D cells were incubated for 4 hours at (PC with 20 nM H]R5020. The cells were irradiated 2 min with 300 nm UV to photoaffinity label the receptors in situ, then homogenized, and a cytosol was prepared which was subjected to SDS-polyacrylamide gel electrophoresis. Proteins were blotted onto nitrocellulose and PR in the right lane were visualized by immune analysis with MAb AB-52 radioactive proteins in the left lane were visualized by fluorography.

Fio. 2. Plasmin and uPA-catalyzed cleavage of suPAR(I-III). (A) 35S-labeled recombinant suPAR(I-III) was purified on an immunoaffinity column with the domain I-specific mAb R3 immobilized [86], Lane 1 is 10 nM suPAR(I-III), lane 2 is 10 nM suPAR(I-III) incubated for 2 hours at 37 °C with 50 nM plasmin (pli), lane 3 is 10-nM suPAR(I-III) incubated for 20 hours at 37°C with 500-nM uPA, and lane 4 is 35S-labeled domain I purified from cell culture media on an immunoaffinity column with the domain I-specific mAb R9 immobilized, after removing suPAR (I—III) from the media by immunoaffinity chromatography, employing the domain Ill-specific mAb R2. (B) Ten nM suPAR(I-III) was preincubated with 67 nM of the indicated mAbs for 2 hours at 37°C prior to addition of either 50 nM plasmin (lanes 2,3,4, and 6) or 500 nM uPA (lane 5) and continued incubation for 2 or 20 hours at 37 °C. Lane 1 is suPAR(I-III) alone, lane 2 is suPAR(I-III) incubated with plasmin only, lane 3 shows preincubation with a subtype control mAb, lanes 4 and 5 show preincubation with mAb R3, lane 6 shows preincubation with the domain Ill-specific mAb R4. The radioactive samples have been separated by SDS-PAGE prior to autoradiography of the dried gel. 

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