Kuroki M, Fernsten P D, Wunderlich D, Colcher D, Simpson J F, Poole D J, Schlom J
Laboratory of Tumor Immunology and Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892.
Cancer Res. 1990 Aug 15;50(16):4872-9.
Monoclonal antibody (MAb) B72.3 has been shown to be of potential utility in the management of human carcinoma via its use in (a) the targeting of carcinoma lesions in colorectal and ovarian cancer patients, (b) immunohistochemical analyses of biopsies and effusions, and (c) serum assays to help define the presence of carcinoma. The B72.3-reactive antigen, designated tumor-associated glycoprotein 72 (TAG-72), has been characterized as a high molecular weight glycoprotein with the properties of a mucin. We report here the utilization of MAb B72.3 and 18 second generation MAbs (generated using purified TAG-72 obtained from a colon carcinoma xenograft as immunogen) to construct a serological map of the TAG-72 molecule. The generation and initial characterization of 10 of the second generation MAbs have been described previously; in addition, eight previously unreported MAbs were used. All 19 MAbs produced immune precipitate lines against purified TAG-72 in double immunodiffusion, indicating that each epitope recognized by a single MAb is present at least twice on the TAG-72 molecule. Immunodepletion analyses utilizing 11 of the anti-TAG-72 MAbs indicated that each recognizes the same molecule or population of molecules. Nineteen competition radioimmunoassays were developed and 19 purified competitor immunoglobulins were used in each assay. The patterns of cross-competition indicated the presence of a complex array of tumor-associated epitopes on the TAG-72 molecule. Some of the MAbs recognized epitopes that were structurally or spatially related to one another, but none appeared to recognize identical epitopes. The spectrum of inhibitory reactivities of these MAbs for TAG-72 binding varied from extremely restricted to more broad inhibition. The serological mapping studies reported here provide information as to the range and nature of the epitopes expressed on the TAG-72 molecule, help form the basis for selecting alternative anti-TAG-72 MAbs for use in potential clinical applications, and further define the nature of this oncofetal antigen.
单克隆抗体（MAb）B72.3已显示出在人类癌症治疗中具有潜在用途，其应用包括：（a）针对结直肠癌和卵巢癌患者的癌灶进行靶向；（b）对活检组织和积液进行免疫组织化学分析；（c）血清检测以帮助确定癌症的存在。B72.3反应性抗原，即肿瘤相关糖蛋白72（TAG-72），已被鉴定为一种具有粘蛋白特性的高分子量糖蛋白。我们在此报告利用MAb B72.3和18种第二代单克隆抗体（使用从结肠癌异种移植瘤中获得的纯化TAG-72作为免疫原产生）构建TAG-72分子的血清学图谱。先前已描述了10种第二代单克隆抗体的产生和初步特性；此外，还使用了8种先前未报道的单克隆抗体。所有19种单克隆抗体在双向免疫扩散中均针对纯化的TAG-72产生免疫沉淀线，表明单个单克隆抗体识别的每个表位在TAG-72分子上至少存在两次。利用11种抗TAG-72单克隆抗体进行的免疫去除分析表明，每种抗体识别的是同一分子或分子群体。开发了19种竞争性放射免疫测定法，每种测定法使用19种纯化的竞争免疫球蛋白。交叉竞争模式表明TAG-72分子上存在一系列复杂的肿瘤相关表位。一些单克隆抗体识别的表位在结构或空间上相互关联，但似乎没有一个识别相同的表位。这些单克隆抗体对TAG-72结合的抑制反应谱从极其有限到更广泛的抑制不等。此处报道的血清学图谱研究提供了有关TAG-72分子上表达的表位范围和性质的信息，有助于为潜在临床应用中选择替代抗TAG-72单克隆抗体奠定基础，并进一步确定这种癌胚抗原的性质。
