Quantitative radioisotopic assay for hemolytic antibody by employing technetium-99m-labeled erythrocytes
A quantitative radioisotopic assay was developed for hemolytic antibody with erythrocytes preaabeled with technetium-99m (/sup 99m/Tc), a high specific activity metastoble gamma emitter. There was a linear relationship batween the amount of /sup 99m/Tc initially used for labeling and the amount of radioactivity taken up by and subsequertly released from erythrocytes which were subjected to complete hemolysis. Hemolytic antibody titrations were carried out with sheep or mouse erythrocytes which had been labeled with varying amounts of either/sup 99m/ Tc or /sup 51/Cr/ and it was concluded that 1 mCi of /sup 99m/Tc or 100 mu Ci of /sup 51/Cr was sufficient to label adequate ly the target cells. The same mean log/sub 2/ endpoint titers were detected in parallel titrations with either mouse anti-sheep RBC serum or an H-2 alloantiserum although the absolute gamma counts of released radioactivity were up to 15 times greater when /sup 99m/Tc erythrocytes were employed. In contrast to these data on the titration of hemolytic antibodies, it was not possible to use /sup 99m/Tclabeaed murine thymocytes or lymphocytes as target cells in assays for cytolytic activity of high titer rabbit anti-mouse lymphocyte sera or an H-2 alloantiserum. The principai advantages of /sup 99m/Tc compared to /sup 51/Cr are its high specific activity, low spontaneous release, and non-reutilizability. From our studies it can be concluded that /sup 99m/Tc can be successfully employed fur the quantitative datermination of hemolytic antibodies and that its favorable physical characteriatics and ready availability suggest that it may replace /sup 51/Cr as a label of choice for erythrocytes. (auth)
- Research Organization:
- Univ. of Kansas Medical Center, Kansas City
- NSA Number:
- NSA-29-021226
- OSTI ID:
- 4351398
- Journal Information:
- J. Immunol., v. 112, no. 2, pp. 756-762, Other Information: Orig. Receipt Date: 30-JUN-74
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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