Lan Q, Huang Q, Bao S
Department of Neurosurgery, Suzhou Medical College, Jiangsu, China.
J Neuroimaging. 1996 Apr;6(2):131-5. doi: 10.1111/jon199662131.
The imaging characteristics of monoclonal antibody SZ39 against glioma were evaluated in glioma-bearing nude mice. Monoclonal antibody SZ39 is a murine IgG2a that reacts with a glycoprotein epitope (molecular weight 180,000), a human glioma-associated membrane antigen. Monoclonal antibody SZ39 was labeled with 131I using a modified chloramine T method. Each glioma-bearing nude mouse was given 50 microCi/40 micrograms of the experimental agent, 131I-labeled monoclonal antibody, or 50 microCi/46 micrograms of a control agent, 131I-labeled monoclonal antibody C50, an antibody against colon cancer. Single-photon emission computed tomography (SPECT) was performed every 24 hours in the first week after administration. Glioma-bearing nude mice were killed in groups of 3 at 24 hours and daily up to 72 hours. The ratio of radioactivity uptake in glioma to normal organs was calculated. After administration of the labeled SZ39, glioma was visualized with SPECT on days 1 to 7, particularly at 72 hours. There was no accumulation of radioactivity in glioma with the labeled C50 antibody. All glioma-organ ratios increased with time. At 72 hours, the ratio of glioma to brain was 22.46 and of the other organs was 2.64 on average. SZ39 had a relatively low endocytosis rate and was favorable for 131I labeling. These characteristics were helpful to reduce free 131I in the blood and reduce the uptake by other organs. The results suggest that 131I-labeled SZ39 selectively accumulates in glioma, representing a potential strategy for SPECT imaging of these lesions.
在荷胶质瘤裸鼠中评估了抗胶质瘤单克隆抗体SZ39的成像特性。单克隆抗体SZ39是一种鼠IgG2a，可与人胶质瘤相关膜抗原（一种分子量为180,000的糖蛋白表位）发生反应。采用改良氯胺T法用131I标记单克隆抗体SZ39。每只荷胶质瘤裸鼠给予50微居里/40微克的实验剂（131I标记的单克隆抗体）或50微居里/46微克的对照剂（131I标记的抗结肠癌抗体C50）。给药后的第一周，每24小时进行一次单光子发射计算机断层扫描（SPECT）。荷胶质瘤裸鼠在24小时时成组处死3只，之后每天处死直至72小时。计算胶质瘤与正常器官的放射性摄取比值。给予标记的SZ39后，在第1至7天用SPECT可观察到胶质瘤，尤其是在72小时时。标记的C50抗体在胶质瘤中无放射性聚集。所有胶质瘤与器官的比值均随时间增加。在72小时时，胶质瘤与脑的比值平均为22.46，与其他器官的比值平均为2.64。SZ39具有相对较低的内吞率，有利于131I标记。这些特性有助于减少血液中的游离131I并减少其他器官的摄取。结果表明，131I标记的SZ39可选择性地在胶质瘤中聚集，这代表了对这些病变进行SPECT成像的一种潜在策略。
