Ozaki K, Ozaki S, Kosaka M, Saito S
1st Department of Internal Medicine, School of Medicine, University of Tokushima, Japan.
Tokushima J Exp Med. 1996 Jun;43(1-2):7-15.
We have examined the localization in the tumor of anti-HM1.24, a murine monoclonal antibody which is specific for human plasma cell-associated antigen. The biodistribution and imaging were compared in severe combined immunodeficiency mice bearing human plasmacytoma (RPMI 8226) xenografts after intravenous injection of radiolabeled anti-HM1.24. The mean tumor uptake of 1 microCi of 125I-labeled anti-HM1.24 was 2.98% injected dose per g of tissue (%ID/g) at day 1 and increased to 5.50% ID/g at day 4, whereas tumor uptake values of control IgG was always less than 1.36% ID/g. The tumor localization indices ranged between 2.35 and 6.03 at day 1 to 4 after injection. Anti-HM1.24 showed no evidence of targeting to normal tissues except a splenic uptake, however, splenic targeting was abolished by the blocking of Fc receptors in the reticuloendothelium. In most cases, tumor-to-tissue ratios were greater than 2 at day 4, indicative of tumor selectivity for anti-HM1.24. Radioimaging with 10 microCi of 131I-labeled anti-HM1.24 showed that 25% of the total-body count were localized in the tumor and the tumors could be visualized without subtraction techniques at day 4. Furthermore, the penetration and binding of anti-HM1.24 to the tumor cells were confirmed by autoradiographic studies. These findings indicate that anti-HM1.24 is a potent agent for detection and targeting of human plasmacytoma.
我们检测了抗HM1.24（一种对人浆细胞相关抗原具有特异性的鼠单克隆抗体）在肿瘤中的定位。在静脉注射放射性标记的抗HM1.24后，对携带人浆细胞瘤（RPMI 8226）异种移植物的严重联合免疫缺陷小鼠的生物分布和成像进行了比较。1微居里的125I标记抗HM1.24在第1天的平均肿瘤摄取量为每克组织2.98%注射剂量（%ID/g），并在第4天增加到5.50% ID/g，而对照IgG的肿瘤摄取值始终低于1.36% ID/g。注射后第1至4天，肿瘤定位指数在2.35至6.03之间。抗HM1.24除了脾脏摄取外，没有显示出靶向正常组织的证据，然而，网状内皮系统中Fc受体的阻断消除了脾脏靶向。在大多数情况下，第4天时肿瘤与组织的比率大于2，表明抗HM1.24对肿瘤具有选择性。用10微居里的131I标记抗HM1.24进行放射性成像显示，全身计数的25%位于肿瘤中，并且在第4天时无需减法技术即可观察到肿瘤。此外，放射自显影研究证实了抗HM1.24对肿瘤细胞的穿透和结合。这些发现表明，抗HM1.24是检测和靶向人浆细胞瘤的有效试剂。
