Fiszman G, Koss A, Glait H, Horenstein A
Centro Oncológico de Medicina Nuclear, Universidad de Buenos Aires, Argentina.
Haematologica. 1994 Mar-Apr;79(2):112-8.
Monoclonal antibodies (mAb) specific for the oligosaccharide epitopes of glycoproteins or glycolipids, such as blood group antigens, are powerful tools for studying the antigenic structure of normal and pathological cells and tissues. Anti-A human red blood cell monoclonal antibodies were produced by immunizing mice with normal cells, but only a few fulfilled the conditions necessary for revealing qualitative differences among A-antigens. Only those produced by hybridomas obtained from mice immunized with human tumor antigens specifically recognize A1 and A2 blood group antigens. We report here several immunological properties of the A-antigen defined by a mAb raised against the tumor-associated carcinoembryonic antigen.
The hybridoma B2C114, obtained as a result of the fusion of spleen cells from mice immunized with the carcinoembryonic antigen and a murine myeloma cell line, produces a mAb which reacts specifically against erythrocytes bearing the A blood-group antigen. The monoclonal antibody showed a high stability and a low dissociation rate from the antigen/antibody complex formed with adult A1, A2, A2B and cord blood samples. The antibody was able not only to discriminate between A1- and A2-RBC but also to detect kinetic differences among A-sites. On the one hand B2C114, reactive with the glycosidic moiety of the A-antigen, can discern at least two qualitatively different epitopes expressed on the A1-RBC surface, with a total number of A sites that is in close agreement with the figures already described for A1-RBC. On the other hand, A2-RBC shows a single phenotype that is kinetically similar to A1-low affinity binding sites. This antibody also labelled spontaneous and chemically-induced murine tumors as well as human tumors. Its reactivity with colon carcinoma frozen specimens obtained from O- and B-blood group patients indicated expression of an incompatible A-antigen. The immunochemical properties of B2C114 described here give support to our purpose of employing this mAb as a blood group reagent as well as a histopathological probe for in vitro and in vivo cancer diagnosis.
针对糖蛋白或糖脂（如血型抗原）的寡糖表位具有特异性的单克隆抗体（mAb），是研究正常及病理细胞和组织抗原结构的有力工具。抗A人红细胞单克隆抗体是通过用正常细胞免疫小鼠产生的，但只有少数满足揭示A抗原间质量差异所需的条件。只有那些由用人肿瘤抗原免疫的小鼠获得的杂交瘤产生的抗体才能特异性识别A1和A2血型抗原。我们在此报告一种针对肿瘤相关癌胚抗原产生的单克隆抗体所定义的A抗原的几种免疫学特性。
用癌胚抗原免疫的小鼠脾细胞与鼠骨髓瘤细胞系融合得到杂交瘤B2C114，它产生一种单克隆抗体，该抗体与携带A血型抗原的红细胞发生特异性反应。该单克隆抗体表现出高稳定性以及与成年A1、A2、A2B和脐带血样本形成的抗原/抗体复合物的低解离率。该抗体不仅能够区分A1和A2红细胞，还能检测A位点之间的动力学差异。一方面，与A抗原糖苷部分反应的B2C114能够识别A1红细胞表面表达的至少两种质量上不同的表位，A位点总数与已描述的A1红细胞的数据非常一致。另一方面，A2红细胞表现出单一表型，其动力学与A1低亲和力结合位点相似。该抗体还标记了自发和化学诱导的鼠肿瘤以及人类肿瘤。它与从O型和B型血患者获得的结肠癌冷冻标本的反应性表明存在不相容的A抗原表达。这里描述的B2C114的免疫化学特性支持我们将这种单克隆抗体用作血型试剂以及用于体外和体内癌症诊断的组织病理学探针的目的。
