小鼠髓系树突状细胞的体外扩增和超微结构

背景:树突状细胞可激发初始型T细胞,是目前所知机体功能最强的专职抗原递呈细胞,但对其超微结构的研究鲜见报道.目的:观察小鼠髓系树突状细胞不同发育阶段以及CD40配基化和肿瘤坏死因子α刺激后树突状细胞的超微结构特征.方法:无菌取小鼠骨髓前体细胞,采用粒细胞一巨噬细胞集落刺激因子和白细胞介素4联合方案体外诱导获得未成熟树突状细胞,负载早期凋亡的肿瘤细胞后采用小鼠CD40L转基因CHO细胞和肿瘤坏死因子α刺激48 h,按常规方法制备超薄切片,透射电镜观察树突状细胞的超微结构特征.结果与结论:前体细胞及未成熟树突状细胞内有清晰可见的吞饮泡,未成熟树突状细胞的胞质内可见"C"形和环形溶酶体;凋亡肿瘤细胞负载的树突状细胞可见凋亡小体被吞噬或包裹的现象,小鼠CD40L转基因CHO细胞和肿瘤坏死因子α均可促进树突状细胞成熟,但肿瘤坏死因子α作用后,部分树突状细胞有自噬和凋亡改变.结果提示,小鼠骨髓来源树突状细胞在不同分化发育阶段有其特殊的超微结构表现,肿瘤坏死因子α可介导树突状细胞发生自噬和凋亡.

In vitro amplification and ultrastructure of dendritic cells from mouse bone marrow

BACKGROUND: Denddtic cells (DCs) constitute the dominant population of antigen presenting cells (APCs) by possessing potent ability to initiate T cell immunity. The ultrastructure study of DCs is less reported. OBJECTIVE: To investigate the ultrastructure of DCs from mice bone marrow at different maturation stages, and the morphology of DCs between CD40 ligation and tumor necrosis factor-alpha (TNF-α) stimulation in vitro. METHODS: Mice myeloid DCs were generated from bone marrow in vitro using granulocyte-macrophage colony-stimulating factor (GM-CSF)and interleukin-4 (IL-4). Immature DCs were loaded with apoptotic tumor cells (AP-DC), and AP-DC was then stimulated with CD40L-CHO cells and TNF-α for 48 hours, respectively. DCs were routinely sectioned, and ultrastructure was observed under transmission electron microscope. RESULTS AND CONCLUSION: Immature DCs showed a few short and blunt cytoplasmic processes, there were specific morphology lysosomes that liked earphone in some cells; DCs engulfing the apoptotic bodies were observed; sub-cellular structures between CD40 ligation and TNF-α stimulated DCs were different, the former had typical morphology of mature DCs which exhibited many dendritic protrusions, however, some DCs displayed apoptosis and autophagy after TNF-α stimulation. In a conclusion, CD40 ligation plays an essential role in myeloid DCs differentiation and maturation, TNF-α can mediate apoptosis and autophaqy of DCs.