An optimized method for measuring cyclosporin a with 125I-labeled cyclosporin
Felder, R.A.; Mifflin, T.E.; Bastani, B.
Clinical Chemistry 32(7): 1378-1382
1986
ISSN/ISBN: 0009-9147 PMID: 3521944 Document Number: 272236
We evaluated the use of the new iodinated ligand for the in vitro measurement of cyclosporin A by radioimmunoassay (RIA). Substitution of the iodinated cyclosporin (125I-CyA) for the corresponding tritium-labeled analog (3H-CyA) considerably simplifies and accelerates the currently available RIA, and improves its precision. Analysis of the respective dose-response curves showed that the 50% B0 value was lower for the 125I-CyA assay than for the 3H-CyA assay (37 vs 77 micrograms/L). Use of whole-blood specimens minimized interferences from temperature and hematocrit. We conclude that the use of 125I-CyA in a commercially available RIA for whole-blood specimens is accessible to most laboratories and provides rapid, reproducible data for management of transplant patients.