Rituximab的碘标记方法及其在正常小鼠体内的生物分布

Iodination Conditions of Rituximab and Its Biodistribution in Mice

采用N-溴代琥珀酰亚胺(NBS)方法对Rituximab(美罗华)进行标记,并优化标记条件。系统考察了反应时间、NBS用量、反应温度、反应体积、pH值及KI的加入等条件对125I-Rituximab标记率的影响,用ITLC-SG测定标记率和放化纯度。确定最佳条件为:反应时间2～3 min、pH 7.0、室温、反应体积80μL为反应最优条件。在最佳条件下,5次标记实验标记物的放化纯度为93.9%±1.6%。采用体外结合实验测定储存不同时间131I-Rituximab的免疫活性,结果表明随着131I-Rituximab储存时间的增加免疫活性下降。正常小鼠静脉注射131I-Rituximab后体内分布显示血液中放射性分布较高,并可持续6 d,表明131I-Rituximab体内稳定。异常毒性实验结果表明131I-Rituximab毒性低。

The effects of reaction time, amount of the NBS, reaction temperature, volume and pH on the labeling efficiency of ^125I-Rituximab are systematically studied. The labeling efficiency is more than 92% under the optimum labeling conditions. The labeling efficiency and radiochemical purity are detected by ITLC-SG. Binding test between Raji cells and ^125I- Rituximab are carried out. The results demonstrate that the binding of ^131I-Rituximab and Raji cells is time dependent. The biodistribution in mice is detected. High distribution of radioactivity that lasted for 6 days is detected in blood after injection of ^131I-Rituximab. It indicates the stability of ,^131I-Rituximab in vivo. The acute toxicity of the ^131I-Rituximab is low.