Immunochemical studies of mucin-type glycoproteins

为了揭示粘蛋白的特征结构，我们建立了粘蛋白特异性单克隆抗体MSW 113、MLS 102和MLS 128。用msw113作为免疫亲和剂，从人初乳中分离出具有线性和支链结构的低聚糖。在同一分子中，一些低聚糖除了具有唾液酰le ^a外，还具有唾液酰le ^x的行列式。这表明MSW 113具有广泛的结合特异性。MSW 113在与多种结构的低聚糖发生反应时，特异性地识别了sialyl-Le^a结构，这使MSW 113成为检测患者血清中癌症抗原的有效试剂。分别确定了MLS 102和MLS 128的表位。MLS 102是一种抗唾液酰n抗体。从羊颌下粘蛋白（OSM）中分离到具有簇状结构的Sia-GalNAc-Ser/Thr糖肽。在去除唾液酸后，糖肽被证明是抗tn抗体MLS 128的表位。由三个或四个连续的GalNAc-Ser/Thr序列组成的簇结构最初在OSM中发现，但随后在Tn红细胞的n-糖蛋白A和t淋巴样细胞Jurkat的白细胞中也发现了类似的簇结构。唾液中Tn和Tn抗原被认为是肿瘤的标志物。事实上，MLS 102和MLS 128在组织化学染色癌症组织方面是有效的，因此是癌症患者体内显像剂的潜在候选者。从癌细胞和癌症患者的胸膜液中分离出粘蛋白，并对其碳水化合物成分进行了分析。像OSM一样，这些粘蛋白至少同时表达唾液中的Tn和Tn抗原。决定这两种抗原共表达的因素仍然未知，因为共表达发生在糖转移酶包括唾液转移酶发生的情况下。

To reveal the characteristic structures of mucins, mucin-specific monoclonal antibodies, MSW 113, MLS 102 and MLS 128, have been established. Using MSW 113, as an immunoaffinity agent, oligosaccharides have been isolated from human colostrum, all of which have the sialyl-Le^a determinant in linear and branched structures. Some of the oligosaccharides have the sialyl-Le^x determinant in addition to the sialyl-Le^a in the same molecule. These indicate that MSW 113 have a broad binding specificity.MSW 113 is in fact superior to NS 19-9, recognizing sialyl-Le^a structure specifically, in reacting with oligosaccharides having a variety of structures, which made MSW 113 a useful reagent to detect cancer antigens in sera of patients.Epitopes for MLS 102 and MLS 128, respectively, have been determined. MLS 102 is an anti-sialyl Tn antibody. From ovine submaxillary mucin (OSM), glycopeptides with a cluster structure, composed of Sia-GalNAc-Ser/Thr, have been isolated. After the removel of sialic acid, the glycopeptides turned out to be the epitope for MLS 128, an anti-Tn antibody. The cluster structure composed of three or four consecutive sequences of GalNAc-Ser/Thr was initially found in OSM,but similar clusters have then been found in Tn-glycophorin A from Tn erythrocyte and leukosialin from a T-lymphoid cell, Jurkat.Sialyl Tn and Tn antigens have been regarded as tumor marker. In fact, MLS 102 and MLS 128 are effective in staining histochemically cancer tissues, thus being potentially candidates for in vivo imaging agents for cancer patients.Mucins were isolated from cancer cells and pleural fluids from cancer patients and their carbohydrate moieties were analyzed. Like OSM,these mucins express at least both sialyl Tn and Tn antigens. The factors which determine the co-expression of these two antigens remain unknown, since the co-expression occurs in the circumstance where sugar transferases including sialyl transferase occur.