Department of Pathology and Immunology, University of Geneva Medical School Geneva, Switzerland.
Front Immunol. 2013 Mar 6;4:59. doi: 10.3389/fimmu.2013.00059. eCollection 2013.
Plasmacytoid dendritic cells (pDCs) are a particular subset of DCs that link innate and adaptive immunity. They are responsible for the substantial production of type 1 interferon (IFN-I) in response to viral RNA or DNA through activation of TLR7 and 9. Furthermore, pDCs present antigens (Ag) and induce naïve T cell differentiation. It has been demonstrated that pDCs can induce immunogenic T cell responses through differentiation of cytotoxic CD8(+) T cells and effector CD4(+) T cells. Conversely, pDCs exhibit strong tolerogenic functions by inducing CD8(+) T cell deletion, CD4(+) T cell anergy, and Treg differentiation. However, since IFN-I produced by pDCs efficiently activates and recruits conventional DCs, B cells, T cells, and NK cells, pDCs also indirectly affect the nature and the amplitude of adaptive immune responses. As a consequence, the precise role of Ag-presenting functions of pDCs in adaptive immunity has been difficult to dissect in vivo. Additionally, different experimental procedures led to conflicting results regarding the outcome of T cell responses induced by pDCs. During the development of autoimmunity, pDCs have been shown to play both immunogenic and tolerogenic functions depending on disease, disease progression, and the experimental conditions. In this review, we will discuss the relative contribution of innate and adaptive pDC functions in modulating T cell responses, particularly during the development of autoimmunity.
浆细胞样树突状细胞（pDCs）是一种特殊的树突状细胞亚群，它连接着先天免疫和适应性免疫。pDCs 通过激活 TLR7 和 TLR9，对病毒 RNA 或 DNA 作出反应，大量产生 I 型干扰素（IFN-I）。此外，pDCs 还呈递抗原（Ag）并诱导初始 T 细胞分化。研究表明，pDCs 可通过诱导细胞毒性 CD8+T 细胞和效应性 CD4+T 细胞的分化来诱导免疫原性 T 细胞反应。相反，pDCs 通过诱导 CD8+T 细胞的缺失、CD4+T 细胞的失能和 Treg 分化，表现出强烈的耐受功能。然而，由于 pDCs 产生的 IFN-I 能有效地激活和募集常规树突状细胞、B 细胞、T 细胞和 NK 细胞，pDCs 也会间接影响适应性免疫反应的性质和幅度。因此，pDCs 呈递 Ag 的功能在适应性免疫中的精确作用在体内很难被剖析。此外，不同的实验程序导致了关于 pDC 诱导的 T 细胞反应结果的相互矛盾的结果。在自身免疫的发展过程中，pDCs 被证明具有免疫原性和耐受性功能，具体取决于疾病、疾病进展和实验条件。在这篇综述中，我们将讨论先天和适应性 pDC 功能在调节 T 细胞反应中的相对贡献，特别是在自身免疫的发展过程中。
