Charactrization of human colon cancer associated carbohydrate antigens.

单克隆抗体是针对癌细胞表面糖蛋白和糖脂的碳水化合物部分产生的，已被证明在检测癌症相关抗原方面是有用的。我们以人结直肠癌细胞系LS180和SWI116为免疫原，固定化糖肽为探针，制备了多种此类单克隆抗体，用于筛选杂杂瘤。其中一种名为MLS102的抗体与癌症相关的唾液- tn抗原以及羊、牛和猪的颌下黏液发生反应。对这些粘蛋白的反应性随NeuAc α 2 - bbb6 GalNAc α 1 ->Ser/Thr（sialyl-Tn）含量的变化而变化。抗原决定因子随后被鉴定为多肽链上的一簇唾液酰- tn残基。另一种单克隆抗体，称为MLS103，与正常黏液型糖蛋白和糖脂中的碳水化合物链反应。用免疫亲和层析法从LS180细胞裂解液和废培养基中分离出粘蛋白抗原。MLS102抗原的氨基酸组成为典型的粘蛋白，主要氨基酸为丝氨酸、苏氨酸和脯氨酸。碳水化合物分析表明，MLS102抗原由0-linked NeuAc alpha2 - bbb6 GalNAc（56%）、n -乙酰半乳糖胺（25%）和未表征的硫酸低聚糖组成。MLS103抗原与MLS102抗原在氨基酸和碳水化合物组成上存在差异。大多数碳水化合物的0链比双糖大。免疫化学和化学分析表明，MLS103抗原的抗原决定因素为Lewis A血型抗原，并且MLS103抗原具有几个特征结构，包括与核心区域n -乙酰半乳糖残基连接的半乳糖。用MLS102和MLS103对LS180细胞进行免疫染色，发现两种抗原的表达具有异质性。上述结果表明，MLS102抗原的表达可能是由于将半乳糖残基转移到核心结构的半乳糖转移酶控制缺陷，或者可能是由于硫酸盐对碳水化合物链的加速修饰，导致分子上大的低聚糖链丢失。少

Monoclonal antibodies, which were raised against the carbohydrate moieties of glycoproteins and glycolipids on cancer cell surfaces, have proved useful in the detection of carcer associated antigens. We have produced many such monoclonal antibodies, using human colorectal cancer cell lines, LS180 and SWI116, as immunogens and immobilized glycopeptides as probes for screening hybridomas.One of the antibodies, called MLS102, reacted with the carcer associated sialyl-Tn antigen, and with ovine, bovine and porcine submaxillary mucins. The reactivity toward these mucins varied in parallel with the NeuAc alpha2 ->6 GalNAc alpha1 ->Ser/Thr(sialyl-Tn)content. The antigenic determinant was then identified as a cluster of sialyl-Tn residues on the polypeptide chain.Another monoclonal antibody, called MLS103, reacted with the carbohydrate chain in the normal mucin-type glycoproteins and glycolipids.The mucin antigens were isolated by immunoaffinity chromatography from cell lysates and spent mediu … More m of LS180 cells. The amino acid composition of the MLS102 antigen was typical of mucins, containing serine, threonine and proline as major amino acids. The carbohydrate analysis revealed that the MLS102 antigen was composed of 0-linked NeuAc alpha2 ->6 GalNAc(56%), N-acetylgalactosamine(25%), and uncharacterized sulfated oligosaccharides.The MLS103 antigen differed from the MLS102 antigen in both amino acid and carbohydrate compositions. Most of the 0-linked carbohydrate chains were larger than disaccharide. Immuniochemical and chemical analyses showed that the antigenic determinant of the MLS103 was Lewis A blood group antigen, and that the MLS103 antigen possessed several characteristic structures involving galactose linked to N-acetylgalactosamine residue in the core region.Immunostaining of LS180 cells using MLS102 and MLS103 revealed that the cells are heterogeneous with respect to the expression of both antigens.Above findings show that the expression of the MLS102 antigen may depend on the defective control of galactosyltransferase which transfers galactose residue to the core structure, or may be due to the acceralated modification of carbohydrate chains with sulfate, which results in the loss of large oligosaccharide chains on the molecule. Less