Lee Yen-Hua, Liao Yi-Jen, Huang Chin-Han, Chang Fu-Ling, Fan Ting-Hsi, Twu Yuh-Ching
Department of Biotechnology and Laboratory Science in Medicine, National Yang-Ming University, Taipei, Taiwan.
Department of Medical Research, Mackay Memorial Hospital, New Taipei City, Taiwan.
Transfusion. 2017 Apr;57(4):1040-1051. doi: 10.1111/trf.13982. Epub 2017 Mar 24.
The aberrant glycosylation on proteins and lipids has been implicated in malignant transformations for promoting the tumorigenesis, metastasis, and evasion from the host immunity. The I-branching β-1,6-N-acetylglucosaminyltransferase, converting the straight i to branched I histo-blood group antigens, reportedly could influence the migration, invasion, and metastasis of solid tumors.
We first chose the highly cytotoxic natural killer (NK)-92MI cells as effector against leukemia for this cell line has been used in several clinical trials. Fluorescence-activated cell sorting and nonradioactive cytotoxicity assay were performed to reexamine the role of NK-activating receptors, their corresponding ligands, and the tumor-associated carbohydrate antigens in this NK-92MI-leukemia in vitro system. The I role on cytotoxic mechanism was further studied especially on the effector-target interactions by cytotoxic analysis and conjugate formation assay.
We showed that expression levels of leukemia surface ligands for NK-activating receptors did not positively reflect susceptibility to NK-92MI. Instead, the expression of I antigen on the leukemia cells was found important in mediating the susceptibility to NK targeting by affecting the interaction with effector cells. Furthermore, susceptibility was shown to dramatically increase while overexpressing branched I antigens on the I- cells. By both conjugate and cytotoxicity assay, we revealed that the presence of I antigen on leukemia cells enhanced the interaction with NK-92MI cells, increasing susceptibility to cell-mediated lysis.
In our system, branched I antigens on the leukemia were involved in the immunosurveillance mediated by NK cells specifically through affecting the effector-target interaction.
蛋白质和脂质上的异常糖基化与恶性转化有关，可促进肿瘤发生、转移及逃避宿主免疫。据报道，将直链i型组织血型抗原转化为分支I型的I分支β-1,6-N-乙酰葡糖胺基转移酶可能会影响实体瘤的迁移、侵袭和转移。
我们首先选择了具有高细胞毒性的自然杀伤（NK）-92MI细胞作为抗白血病效应细胞，因为该细胞系已用于多项临床试验。进行了荧光激活细胞分选和非放射性细胞毒性测定，以重新审视NK激活受体、其相应配体以及肿瘤相关碳水化合物抗原在这个NK-92MI-白血病体外系统中的作用。通过细胞毒性分析和共轭形成测定，进一步研究了I在细胞毒性机制中的作用，特别是在效应细胞与靶细胞的相互作用方面。
我们发现，NK激活受体的白血病表面配体的表达水平并不能正向反映对NK-92MI的敏感性。相反，发现白血病细胞上I抗原的表达在介导对NK靶向的敏感性方面很重要，它通过影响与效应细胞的相互作用来实现。此外，在I-细胞上过表达分支I抗原时，敏感性显著增加。通过共轭和细胞毒性测定，我们揭示白血病细胞上I抗原的存在增强了与NK-92MI细胞的相互作用，增加了对细胞介导裂解的敏感性。
在我们的系统中，白血病上的分支I抗原通过影响效应细胞与靶细胞的相互作用，特异性地参与了NK细胞介导的免疫监视。
