Miyake M, Kohno N, Nudelman E D, Hakomori S
Biomembrane Institute, Seattle, Washington.
Cancer Res. 1989 Oct 15;49(20):5689-95.
Previously established human monoclonal antibodies (MAbs) directed to carbohydrate antigens are essentially all IgM class, and show relatively low affinity and low reactivity at 37 degrees C. We report here the establishment of a human IgG3 MAb displaying high affinity antigen-binding activity at 37 degrees C and efficiently activating cellular cytotoxicity directed to human tumor cell lines expressing the polylactosamine antigen. The IgG3 MAb (MH21-134) reacted with the repeated unbranched polylactosamine structure Gal beta 1----4GlcNAc beta 1----3Gal beta 1----4GlcNAc beta 1----3Gal beta 1----R, i.e., nLc6, nLc8, etc., but did not react with sialyl 2----3 or 2----6 substituted derivatives at the terminal Gal. This specificity differs from that of several anti-i antibodies, or human anti-i-like MAbs which react with sialyl 2----3 substituted structures. Directly biotinylated MH21-134 antibody was used in immunohistochemical staining of 154 formalin-fixed, paraffin-embedded tissue sections to study distribution of the antigen. High incidence of positive staining was found in colon cancer (11/17; 65%) and hepatocellular carcinoma (8/12; 67%), followed by large cell and squamous cell carcinoma of lung cancer (10/13; 59%, and 14/26; 54%, respectively). TLC immunostaining of glycolipid extracts from a variety of tumor tissues showed the presence of nLc6 and/or nLc8 in over 50% of cases. The antigens nLc6 and nLc8 were found to be absent from normal colonic epithelia, kidney, and pancreas. Only a weak band corresponding to nLc8 and one corresponding to nLc6 were found in liver and spleen, although all these normal tissues, including gastrointestinal epithelia, lung, liver, spleen, erythrocytes, and lymphocytes, were essentially negative on immunohistology. However, the antigen was found to be highly expressed in myelocytes and weakly in bronchial glands of lung and pancreatic duct epithelia. Nevertheless, expression of unsubstituted, unbranched polylactosamine antigen could be an important basis for induction of humoral immune response against certain types of human cancer, despite its limited expression in normal cells.
先前建立的针对碳水化合物抗原的人源单克隆抗体（MAb）基本上都是IgM类，并且在37℃时显示出相对较低的亲和力和反应性。我们在此报告建立了一种人IgG3 MAb，其在37℃时表现出高亲和力抗原结合活性，并能有效激活针对表达多乳糖胺抗原的人肿瘤细胞系的细胞毒性。IgG3 MAb（MH21-134）与重复的无分支多乳糖胺结构Galβ1----4GlcNAcβ1----3Galβ1----4GlcNAcβ1----3Galβ1----R，即nLc6、nLc8等发生反应，但不与末端Gal上唾液酸2----3或2----6取代的衍生物发生反应。这种特异性不同于几种抗-i抗体或与人唾液酸2----3取代结构发生反应的人抗-i样MAb。直接生物素化的MH21-134抗体用于对154张福尔马林固定、石蜡包埋的组织切片进行免疫组织化学染色，以研究抗原的分布。在结肠癌（11/17；65%）和肝细胞癌（8/12；67%）中发现高阳性染色发生率，其次是肺癌的大细胞和鳞状细胞癌（分别为10/13；59%和14/26；54%）。对来自各种肿瘤组织的糖脂提取物进行TLC免疫染色显示，超过50%的病例中存在nLc6和/或nLc8。发现正常结肠上皮、肾脏和胰腺中不存在抗原nLc6和nLc8。在肝脏和脾脏中仅发现一条对应于nLc8的弱带和一条对应于nLc6的带，尽管所有这些正常组织，包括胃肠道上皮、肺、肝脏、脾脏、红细胞和淋巴细胞，在免疫组织学上基本为阴性。然而，发现该抗原在骨髓细胞中高度表达，在肺支气管腺和胰腺导管上皮中弱表达。尽管未取代、无分支的多乳糖胺抗原在正常细胞中的表达有限，但它可能是诱导针对某些类型人类癌症的体液免疫反应的重要基础。
