Gano L, Patrício L, Marques E, Cantinho G, Pena H, Martins T, Hnatowich D J
Instituto Tecnológico e Nuclear, Estrada Nacional N. 10, Sacavém, Portugal.
Nucl Med Biol. 1998 May;25(4):395-403. doi: 10.1016/s0969-8051(97)00225-4.
The aim of this study was to evaluate the radiochemical behavior, biological distribution, and localization in infection sites in mice of a human polyclonal immunoglobulin (HIG) labelled with 99mTc by a novel MAG3-labelling method. The resulting [99mTc]MAG3-HIG was compared with [99mTc]HIG preparations radiolabelled directly via 2-mercaptoethanol (2-Me) or stannous ion (Sn) reduction and indirectly via 2-iminothiolane (2-Im) conjugation. All preparations showed similar UV and radioactivity HPLC profile to that of native HIG except for 2-Im-HIG, which showed aggregates. The stabilities of the label to challenge with cysteine were similar for all the preparations. By nondenaturing SDS-PAGE, all preparations other than MAG3-HIG showed evidence of lower molecular weight fragments. The tissue distribution 4 and 24 h after intravenous administration of the four preparations were compared in mice previously administered with an isolate of Staphylococcus aureus in one thigh. The pharmacokinetics varied among the different preparations. When prepared via 2-Me, Sn, and 2-Im, both blood clearance and urinary excretion were faster than that of labelled MAG3-HIG. The absolute uptake in the infected thigh at 24 h was significantly higher for HIG labelled via MAG3 and 2-Me vs. the remaining methods. The infected thigh/normal thigh radioactivity ratios were similar at both time points for labelled HIG prepared via 2-Me, 2-Im, and NHS-MAG, methods but was significantly lower at 24 h for HIG prepared via Sn. The radioactive HPLC profiles of serum at 4 and 24 h were similar to that of the radiolabelled injectates. Based on these data we conclude that each radiolabelled HIG preparation studied showed increased localization in infectious foci although [99Tc]MAG3-HIG showed superior radiochemical and biological characteristics under the conditions of this investigation.
本研究的目的是通过一种新型的MAG3标记方法，评估用99mTc标记的人多克隆免疫球蛋白（HIG）在小鼠体内的放射化学行为、生物分布以及在感染部位的定位。将所得的[99mTc]MAG3-HIG与通过2-巯基乙醇（2-Me）或亚锡离子（Sn）还原直接进行放射性标记以及通过2-亚氨基噻吩烷（2-Im）偶联间接进行放射性标记的[99mTc]HIG制剂进行比较。除了显示有聚集体的2-Im-HIG外，所有制剂的紫外和放射性HPLC图谱与天然HIG相似。所有制剂对半胱氨酸攻击的标记稳定性相似。通过非变性SDS-PAGE分析，除MAG3-HIG外的所有制剂均显示出低分子量片段的迹象。在先前于一侧大腿接种金黄色葡萄球菌分离株的小鼠中，比较了四种制剂静脉注射后4小时和24小时的组织分布。不同制剂的药代动力学有所不同。通过2-Me、Sn和2-Im制备时，血液清除率和尿排泄均比标记的MAG3-HIG快。与其余方法相比，通过MAG3和2-Me标记的HIG在24小时时感染大腿的绝对摄取量显著更高。通过2-Me、2-Im和NHS-MAG方法制备的标记HIG在两个时间点的感染大腿/正常大腿放射性比值相似，但通过Sn制备的HIG在24小时时该比值显著较低。4小时和24小时时血清的放射性HPLC图谱与放射性标记注射剂的图谱相似。基于这些数据，我们得出结论，尽管在本研究条件下[99Tc]MAG3-HIG显示出优异的放射化学和生物学特性，但所研究的每种放射性标记HIG制剂在感染灶中的定位均有所增加。
