Vaughan A T, Yankuba S C, Anderson P
NCI Monogr. 1987(3):141-4.
An antibody with human CEA specificity has been labeled with either yttrium-90, scandium-47, or indium-111, via a diethylenetriamine pentaacetic acid (DTPA) link covalently bound to the protein. The clearance of these proteins from the blood of mice can be described by a single exponential; the half-life decreases in the order indium-111 greater than yttrium-90 greater than scandium-47. Associated with the blood clearance is an uptake of radioactivity into the liver; scandium-47 has the highest concentration, indium-111 has the least, and yttrium-90 is intermediate. There is no correlation between these results and the equilibrium stability constants of the metals with DTPA-like ligands. The results obtained show that, in vivo, scandium-47 and yttrium-90 are more easily displaced from DTPA by other ions than is indium-111. They also show that free DTPA is able to extract yttrium-90 and scandium-47, but not indium-111, from the liver of treated animals, indicating that indium-111 is resistant to ligand exchange reactions in vivo. These data indicate that 1) the equilibrium stability constant is not a good indicator of the in vivo stability of metal-labeled proteins and 2) it is possible to manipulate the ion distribution and therefore the dose from scandium-47 and yttrium-90 after injection of the labeled proteins.
一种具有人癌胚抗原（CEA）特异性的抗体已通过与蛋白质共价结合的二亚乙基三胺五乙酸（DTPA）连接体，用钇 - 90、钪 - 47或铟 - 111进行了标记。这些蛋白质从小鼠血液中的清除情况可用单指数函数来描述；半衰期按铟 - 111大于钇 - 90大于钪 - 47的顺序递减。与血液清除相关的是放射性在肝脏中的摄取；钪 - 47的浓度最高，铟 - 111最低，钇 - 90居中。这些结果与金属与类DTPA配体的平衡稳定常数之间没有相关性。所获得的结果表明，在体内，钪 - 47和钇 - 90比铟 - 111更容易被其他离子从DTPA中置换出来。它们还表明，游离的DTPA能够从经处理动物的肝脏中提取钇 - 90和钪 - 47，但不能提取铟 - 111，这表明铟 - 111在体内对配体交换反应具有抗性。这些数据表明：1）平衡稳定常数并非金属标记蛋白质体内稳定性的良好指标；2）在注射标记蛋白质后，有可能操控离子分布，进而操控来自钪 - 47和钇 - 90的剂量。
