Dendritic cells are powerful antigen-presenting cells that are essential for the priming of T cell responses. In addition to providing T-cell-receptor ligands and co-stimulatory molecules for naive T cell activation and expansion, dendritic cells are thought to also provide signals for the differentiation of CD4+ T cells into effector T cell populations. The mechanisms by which dendritic cells are able to adapt and respond to the great variety of infectious stimuli they are confronted with, and prime an appropriate CD4+ T cell response, are only partly understood. It is known that in the steady-state dendritic cells are highly heterogenous both in phenotype and transcriptional profile, and that this variability is dependent on developmental lineage, maturation stage, and the tissue environment in which dendritic cells are located. Exposure to infectious agents interfaces with this pre-existing heterogeneity by providing ligands for pattern-recognition and toll-like receptors that are variably expressed on different dendritic cell subsets, and elicit production of cytokines and chemokines to support innate cell activation and drive T cell differentiation. Here we review current information on dendritic cell biology, their heterogeneity, and the properties of different dendritic cell subsets. We then consider the signals required for the development of different types of Th immune responses, and the cellular and molecular evidence implicating different subsets of dendritic cells in providing such signals. We outline how dendritic cell subsets tailor their response according to the infectious agent, and how such transcriptional plasticity enables them to drive different types of immune responses.

中文翻译：

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树突状细胞的抗原呈递及其对CD4 + T辅助细胞应答的指示。

树突状细胞是强大的抗原呈递细胞，对于引发T细胞反应至关重要。除了提供T细胞受体配体和共刺激分子用于天然T细胞活化和扩增外，树突状细胞还被认为还提供了将CD4 + T细胞分化为效应T细胞群体的信号。树突状细胞能够适应和响应它们所面对的各种感染性刺激并引发适当的CD4 + T细胞反应的机制仅被部分理解。已知在稳态下，树突状细胞在表型和转录谱上都是高度异质的，并且这种可变性取决于发育谱系，成熟阶段以及树突状细胞所处的组织环境。通过提供用于模式识别和toll样受体的配体（在不同的树突状细胞亚群中可变表达）并引发细胞因子和趋化因子的产生来支持先天细胞活化并驱动T细胞分化，暴露于传染原与这种先前存在的异质性相关。在这里，我们审查有关树突状细胞生物学，它们的异质性和不同的树突状细胞亚群的性质的当前信息。然后，我们考虑了开发不同类型的Th免疫应答所需的信号，以及在提供此类信号时涉及树突状细胞不同亚群的细胞和分子证据。我们概述了树突状细胞亚群如何根据传染原调整其反应，