Central Laboratory, the First Affiliated Hospital of Bengbu Medical College, Anhui, PR China.
Tohoku J Exp Med. 2011 Mar;223(3):193-8. doi: 10.1620/tjem.223.193.
Lipid rafts are plasma membrane microdomains that are implicated in diverse signaling pathways in immune cells. Based on the distinct types of T-cell receptors, two T-cell subpopulations have been identified: αβ and γδ T cells. In humans, γδ T cells represent a relatively rare T lymphocyte population but play a critical role in the immune response to infection by Mycobacterium tuberculosis. It has been demonstrated that Mycobacterium tuberculosis antigens (Mtb-Ag) preferentially activate γδ T cells. Thus, we investigated whether lipid rafts are involved in the Mtb-Ag-mediated activation of γδ T cells. Human peripheral blood mononuclear cells (PBMCs) were stimulated with Mtb-Ag, and expression of a lipid raft marker ganglioside GM1 (GM1) was determined by flow cytometry. The aggregation of lipid rafts was evaluated by laser confocal microscopy. Non-stimulated fresh PBMCs minimally expressed GM1 (6.55 ± 2.01%) and had no aggregated rafts in γδ T cells. Mtb-Ag stimulation gradually increased the expression of GM1 in a time-dependent manner. At 72 h, the majority of γδ T cells expressed GM1 (88.69 ± 7.55%). Furthermore, accompanied with the increased expression of GM1, aggregation of lipid rafts became gradually visible in γδ T cells. The aggregated rafts, however, were not evenly distributed and only occurred over a small portion of GM1-positive cells. Pretreatment with methyl-β-cyclodextrin, a cholesterol-depleting reagent, completely inhibited the Mtb-Ag-mediated aggregation of lipid rafts. These results demonstrate that lipid raft aggregation occurs in Mtb-Ag-activated γδ T cells, suggesting that lipid rafts are involved in activation of γδ T cells.
脂质筏是质膜微区，参与免疫细胞中的多种信号通路。根据 T 细胞受体的不同类型，已经鉴定出两种 T 细胞亚群：αβ 和 γδ T 细胞。在人类中，γδ T 细胞代表相对较少的 T 淋巴细胞群体，但在对结核分枝杆菌感染的免疫反应中发挥关键作用。已经证明结核分枝杆菌抗原（Mtb-Ag）优先激活 γδ T 细胞。因此，我们研究了脂质筏是否参与 Mtb-Ag 介导的 γδ T 细胞激活。用 Mtb-Ag 刺激人外周血单核细胞（PBMC），并用流式细胞术测定脂质筏标志物神经节苷脂 GM1（GM1）的表达。通过激光共聚焦显微镜评估脂质筏的聚集。未刺激的新鲜 PBMC 极少量表达 GM1（6.55±2.01%），并且 γδ T 细胞中没有聚集的筏。Mtb-Ag 刺激以时间依赖性方式逐渐增加 GM1 的表达。在 72 小时时，大多数 γδ T 细胞表达 GM1（88.69±7.55%）。此外，随着 GM1 表达的增加，脂质筏的聚集在 γδ T 细胞中逐渐变得可见。然而，聚集的筏不是均匀分布的，仅发生在一小部分 GM1 阳性细胞上。用胆固醇耗竭试剂甲基-β-环糊精预处理完全抑制了 Mtb-Ag 介导的脂质筏聚集。这些结果表明，脂质筏聚集发生在 Mtb-Ag 激活的 γδ T 细胞中，表明脂质筏参与 γδ T 细胞的激活。
