CD1c tetramers detect ex vivo T cell responses to processed phosphomycoketide antigens
CD1c tetramers detect ex vivo T cell responses to processed phosphomycoketide antigens
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DOI：
10.1084/jem.20120624
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发表时间：
2013-04-08
影响因子：
15.3
通讯作者：
Moody, Branch
中科院分区：
文献类型：
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作者：
Ly, Dalam;Kasmar, Anne G.;Moody, Branch
CD1c 在人类树突状细胞 (DC) 和 B 细胞上高密度表达，但其抗原呈递功能在 CD1 家族成员中是最不为人所知的。使用 CD1c 反应性 T 细胞系 (DN6) 完成对结核分枝杆菌脂质的全有机体调查，我们将 C32 磷酸真菌酮 (PM) 鉴定为以前未知的分子和 CD1c 呈递的抗原。 CD1c 结合和真菌酮抗原的呈递绝对需要由聚酮合酶 12 (pks12) 引入的不寻常的、分枝杆菌特异性的脂质分支模式。出乎意料的是，当 DC 和 B 细胞呈递时，一种 TCR 对不同糖基化和非糖基化形式的 mycoketide 产生反应。然而，无细胞系统表明识别仅由去糖基化的磷酸抗原介导。这些研究鉴定了人类 CD1c 系统中天然细菌抗原的抗原处理，表明细胞作用于糖脂，产生由无糖磷酸根阴离子组成的高度简化的新表位。利用这种加工抗原的知识，我们生成了人 CD1c 四聚体，并证明 CD1c-PM 复合物可染色 T 细胞受体 (TCR)，为 CD1c-脂质-TCR 之间的三元相互作用提供了直接证据。此外，负载 PM 的 CD1c 四聚体可检测外周血中的新鲜人类 T 细胞，证明对人类离体 PM 抗原的多克隆反应。
CD1c is expressed with high density on human dendritic cells (DCs) and B cells, yet its antigen presentation functions are the least well understood among CD1 family members. Using a CD1c-reactive T cell line (DN6) to complete an organism-wide survey of M. tuberculosis lipids, we identified C32 phosphomycoketide (PM) as a previously unknown molecule and a CD1c-presented antigen. CD1c binding and presentation of mycoketide antigens absolutely required the unusual, mycobacteria-specific lipid branching patterns introduced by polyketide synthase 12 (pks12). Unexpectedly, one TCR responded to diversely glycosylated and unglycosylated forms of mycoketide when presented by DCs and B cells. Yet cell-free systems showed that recognition was mediated only by the deglycosylated phosphoantigen. These studies identify antigen processing of a natural bacterial antigen in the human CD1c system, indicating that cells act on glycolipids to generate a highly simplified neoepitope composed of a sugar-free phosphate anion. Using knowledge of this processed antigen, we generated human CD1c tetramers, and demonstrate that CD1c-PM complexes stain T cell receptors (TCRs), providing direct evidence for a ternary interaction among CD1c-lipid-TCR. Furthermore, PM-loaded CD1c tetramers detect fresh human T cells from peripheral blood, demonstrating a polyclonal response to PM antigens in humans ex vivo.