Kitagawa H, Ohkouchi E, Fukuda A, Imai K, Yachi A
Jpn J Cancer Res. 1986 Sep;77(9):922-30.
Six murine monoclonal antibodies (mAbs) reactive with carcinoembryonic antigen (CEA) were prepared. Four of these, CA204, CA205, CA206 and CA208, were specific to purified CEA whereas the other two, NA201 and NA203, were also reactive with the non-specific cross-reacting antigen (NCA). These mAbs were all IgG1, except one IgG2a (CA206), with high affinities for CEA. NA203, CA204 and CA208 appear to define three different epitopes on the CEA molecule as determined by competitive binding assay. These mAbs also reacted with CEA-producing cells. The treatment of the cells with tunicamycin did not affect the binding of the mAbs to CEA-producing cells. None of the above mAbs bound to CEA-related antigens, NCA-2, alpha 1-acid glycoprotein, or blood group antigens. The combination of CA208 (solid phase) and CA204 (tracer) was used to construct a sensitive CEA-specific sandwich ELISA to detect CEA in the sera of patients with various malignant and non-malignant diseases. Particularly when CEA values were low in sera from non-cancerous patients, the above mAbs sandwich assay showed reduced background reactivity with NCA-like substances and permitted the detection of CEA at a level as low as 1 ng/ml.
制备了六种与癌胚抗原（CEA）反应的鼠单克隆抗体（mAb）。其中四种，CA204、CA205、CA206和CA208，对纯化的CEA具有特异性，而另外两种，NA201和NA203，也与非特异性交叉反应抗原（NCA）反应。除一种IgG2a（CA206）外，这些mAb均为IgG1，对CEA具有高亲和力。通过竞争性结合试验确定，NA203、CA204和CA208似乎在CEA分子上定义了三个不同的表位。这些mAb也与产生CEA的细胞反应。用衣霉素处理细胞并不影响mAb与产生CEA的细胞的结合。上述mAb均不与CEA相关抗原、NCA-2、α1-酸性糖蛋白或血型抗原结合。使用CA208（固相）和CA204（示踪剂）的组合构建了一种灵敏的CEA特异性夹心ELISA，用于检测各种恶性和非恶性疾病患者血清中的CEA。特别是当非癌症患者血清中的CEA值较低时，上述mAb夹心测定法显示与NCA样物质的背景反应性降低，并允许检测低至1 ng/ml水平的CEA。
