Epstein A L, Chen F M, Taylor C R
Department of Pathology, University of Southern California, School of Medicine, Los Angeles 90033.
Cancer Res. 1988 Oct 15;48(20):5842-8.
Data are presented in support of the hypothesis that malignant tumors, containing abnormally permeable, degenerating cells, can be selectively detected using monoclonal antibodies to intracellular antigens. Biodistribution, imaging, and autoradiographic studies were performed in nude mice transplanted with four different human tumor cell lines to demonstrate the binding of radiolabeled antinuclear monoclonal antibodies within bulky tumors containing necrotic lesions. For these studies, two monoclonal antibodies, designated TNT-1 (IgG2a) and TNT-2 (IgM) were chosen since they were found to bind to abundant nuclear antigens which are retained in permeable, dying cells. F(ab')2 fragments prepared by pepsin digestion were radiolabeled with iodine-125 or iodine-131 by the iodogen method for i.v. administration. Biodistribution studies in nontumor-bearing BALB/c mice at various time intervals revealed normal patterns of antibody excretion with no accumulation of antibody in healthy organs. In contrast, biodistribution studies performed on Day 3 in tumor-bearing nude mice showed high tumor to organ ratios in those animals bearing necrotic tumors. Necrotic regions dissected at necropsy gave tumor to blood ratios as high as 131:1. Transplants having little demonstrable necrosis were found to have low tumor to blood ratios (0.4:1). Sequential imaging studies confirmed the high tumor-to-organ ratios and showed positive tumor imaging as early as 4 h. Autoradiographic studies of excised tumors showed the presence of label selectively in necrotic areas with preferential labeling over the nuclei of degenerating cells. Because of the universal presence of these nuclear antigens and the known prevalence of necrosis in tumors, this approach may be of value for the imaging and treatment of a wide variety of cancers in humans.
所呈现的数据支持这样一种假说，即含有异常通透、正在退化细胞的恶性肿瘤，可利用针对细胞内抗原的单克隆抗体进行选择性检测。在移植了四种不同人类肿瘤细胞系的裸鼠中进行了生物分布、成像和放射自显影研究，以证明放射性标记的抗核单克隆抗体在含有坏死病变的大块肿瘤内的结合情况。对于这些研究，选择了两种单克隆抗体，分别命名为TNT - 1（IgG2a）和TNT - 2（IgM），因为发现它们能与丰富的核抗原结合，而这些核抗原在通透的、即将死亡的细胞中得以保留。通过胃蛋白酶消化制备的F(ab')2片段用碘 - 125或碘 - 131通过碘代法进行放射性标记，用于静脉注射。在不同时间间隔对无肿瘤的BALB/c小鼠进行的生物分布研究显示抗体排泄模式正常，健康器官中无抗体蓄积。相比之下，在荷瘤裸鼠第3天进行的生物分布研究表明，那些患有坏死肿瘤的动物肿瘤与器官的比值很高。尸检时解剖的坏死区域肿瘤与血液的比值高达131:1。几乎没有明显坏死的移植瘤肿瘤与血液的比值较低（0.4:1）。连续成像研究证实了高肿瘤与器官比值，并早在4小时就显示出阳性肿瘤成像。对切除肿瘤的放射自显影研究表明，标记物选择性地存在于坏死区域，在退化细胞的细胞核上有优先标记。由于这些核抗原普遍存在且已知肿瘤中坏死普遍存在，这种方法可能对人类多种癌症的成像和治疗有价值。
