Matsunaga A, Kuroki M, Higuchi H, Arakawa F, Takakura K, Okamoto N, Matsuoka Y
Cancer Res. 1987 Jan 1;47(1):56-61.
Six mouse monoclonal antibodies reactive with carcinoembryonic antigen (CEA) were prepared and used for the analysis of the antigenic heterogeneity of CEA in patient sera. Their reaction specificity and the chemical nature of antigenic epitopes recognized by them were analyzed by radioimmunoassay on the basis of reactivities with different preparations of CEA, normal fecal antigen 2, and nonspecific cross-reacting antigen 2 before and after chemical and/or enzymatic treatment. Two antibodies, F3-30 and F4-82, raised with CEA were reactive with different peptide epitopes on the antigen molecules and revealed a quite universal reactivity with all CEA, normal fecal antigen 2, or nonspecific cross-reacting antigen 2 preparations tested. The serum CEA values obtained with these antibodies were highly correlated with those obtained with conventional radioimmunoassays for CEA. The other four antibodies (F4-11 and F33-37 raised with CEA, F8-52 with normal fecal antigen 2, and F48-60 with nonspecific cross-reacting antigen 2) were found to recognize carbohydrate epitopes with different specificities and revealed very heterogeneous reactivities. The serum CEA values estimated with these four antibodies were highly variable depending on the antibody used, suggesting that the expression of carbohydrate epitopes on the CEA molecules in patient sera was quite heterogeneous. The antigenic heterogeneity of the carbohydrate epitopes was detected even in a single patient serum by affinity chromatography. The causes that give rise to the difference in CEA values between the Roche and the Daiichi kits were analyzed on the basis of reactivities of three groups of patient sera, which showed extremely different ratios for the Roche and Daiichi kits, with monoclonal anti-carbohydrate antibodies. The results obtained suggest that, at least in part, the diversity of antigenic expression on carbohydrate chains on the CEA molecules in patient sera and the variation in specificity or quantity of anti-carbohydrate antibodies in the polyclonal antibody preparations used for the respective assay systems may result in the differences in the estimated CEA values.
制备了六种与癌胚抗原（CEA）反应的小鼠单克隆抗体，并用于分析患者血清中CEA的抗原异质性。基于这些抗体与不同的CEA制剂、正常粪便抗原2和非特异性交叉反应抗原2在化学和/或酶处理前后的反应性，通过放射免疫测定分析了它们的反应特异性以及所识别的抗原表位的化学性质。用CEA制备的两种抗体F3 - 30和F4 - 82与抗原分子上不同的肽表位反应，并对所有测试的CEA、正常粪便抗原2或非特异性交叉反应抗原2制剂显示出相当普遍的反应性。用这些抗体获得的血清CEA值与用传统CEA放射免疫测定获得的值高度相关。发现另外四种抗体（用CEA制备的F4 - 11和F33 - 37、用正常粪便抗原2制备的F8 - 52和用非特异性交叉反应抗原2制备的F48 - 60）识别具有不同特异性的碳水化合物表位，并显示出非常异质的反应性。用这四种抗体估计的血清CEA值因所用抗体而异，表明患者血清中CEA分子上碳水化合物表位的表达非常异质。通过亲和色谱法甚至在单个患者血清中也检测到了碳水化合物表位的抗原异质性。根据三组患者血清的反应性分析了罗氏试剂盒和第一制药试剂盒之间CEA值差异的原因，这三组患者血清对罗氏试剂盒和第一制药试剂盒的比值差异极大，这些血清与单克隆抗碳水化合物抗体反应。所得结果表明，至少部分地，患者血清中CEA分子上碳水化合物链上抗原表达的多样性以及用于各自检测系统的多克隆抗体制剂中抗碳水化合物抗体的特异性或数量的变化可能导致估计的CEA值存在差异。
