Abstract：
Carbohydrate-antigens widely existed on glycoproteins and glycosphingolipids of all mammalian cells play a crucial role in self-defense and immunity. Xeno-reactive antibodies included in natural human sera play a protecting role in an acute phase-rejection of xenotransplantation. In this study, we investigated the effect of an alteration of glycosylation-pattern, caused by human sialyltransferases such as hST3Gal II or hST6GalNAc IV, on human serum mediated cytotoxicity in pig kidney PK15 cells. From LDH cytotoxicity assay, cytotoxicity to human serum was significantly increased in hST3Gal II and hST6GalNAc IV-transfected PK15 cells, as compared to the control. In the hST6Gal I-carrying cells, the cytotoxicity to human serum was rather decreased. Moreover, flow cytometry analysis revealed that an alteration of pig glycosylation-pattern by hST3Gal II or hST6GalNAc IV influences on a binding of human IgM or IgG, respectively, in pig kidney cells, regardless of Gal antigen alteration. Finally, we found that hST6GalNAc IV contributed to increase of terminal disialylated tetrasaccharide structure, disialyl T antigen, as evidenced by increase of the MAL II lectin binding capacity in the hST6GalNAc IV-transfected PK15 cells, compared with control. Therefore, our results suggest that carbohydrate antigens, such as disialyl T antigen, newly synthesized by the ST3Gal II- and ST6GalNAc IV are potentially believed to be new xeno-reactive elements.
摘要：
糖抗原广泛存在于所有哺乳动物细胞的糖蛋白和鞘糖脂上，在自我防御和免疫中起着至关重要的作用。天然人血清中包含的异种反应性抗体在异种移植的急性期排斥中起保护作用。在这项研究中,我们研究了糖基化模式改变的影响，由人唾液酸转移酶如hST3GalII或hST6GalNAcIV引起，人血清介导的猪肾PK15细胞的细胞毒性。从LDH细胞毒性测定，在hST3GalII和hST6GalNAcIV转染的PK15细胞中，对人血清的细胞毒性显着增加，与对照组相比。在携带hST6GalI的细胞中，对人血清的细胞毒性降低。此外，流式细胞术分析显示hST3GalII或hST6GalNAcIV对猪糖基化模式的改变会影响人IgM或IgG的结合，分别,在猪肾细胞中，无论Gal抗原改变。最后,我们发现hST6GalNAcIV有助于末端二唾液酸化四糖结构的增加，二唾液酸T抗原，正如在hST6GalNAcIV转染的PK15细胞中MALII凝集素结合能力的增加所证明的那样，与对照相比。因此,我们的结果表明碳水化合物抗原，如二唾液酸T抗原，新合成的ST3GalII-和ST6GalNAcIV被认为是新的异种反应元素。
