van Vliet Sandra J, García-Vallejo Juan J, van Kooyk Yvette
Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, The Netherlands.
Immunol Cell Biol. 2008 Oct;86(7):580-7. doi: 10.1038/icb.2008.55. Epub 2008 Aug 5.
Dendritic cells (DCs) have an important function in the initiation and differentiation of immune responses, linking innate information to tailored adaptive responses. Depending on the pathogen invading the body, specific immune responses are built up that are crucial for eliminating the pathogen from the host. Host recognition of invading microorganisms relies on evolutionarily ancient, germline-encoded pattern recognition receptors (PRRs) that are highly expressed on the cell surface of DCs, of which the Toll-like receptors (TLRs) are well characterized and recognize bacterial or viral components. Moreover, they bind a variety of self-proteins released from damaged tissues including several heat-shock proteins. The membrane-associated C-type lectin receptors (CLRs) recognize glycan structures expressed by host cells of the immune system or on specific tissues, which upon recognition allow cellular interactions between DCs and other immune or tissue cells. In addition, CLRs can function as PRRs. In contrast to TLRs, CLRs recognize carbohydrate structures present on the pathogens. Modification of glycan structures on pathogens to mimic host glycans can thereby alter CLR interactions that subsequently modifies DC-induced polarization. In this review, we will discuss in detail how specific glycosylation of antigens can dictate both the innate and adaptive interactions that are mediated by CLRs on DCs and how this balances immune activation and inhibition of DC function.
树突状细胞（DCs）在免疫反应的启动和分化中发挥着重要作用，将先天信息与定制的适应性反应联系起来。根据入侵机体的病原体不同，会建立起特定的免疫反应，这对于从宿主体内清除病原体至关重要。宿主对入侵微生物的识别依赖于进化上古老的、种系编码的模式识别受体（PRRs），这些受体在DCs的细胞表面高度表达，其中Toll样受体（TLRs）已得到充分表征，可识别细菌或病毒成分。此外，它们还能结合从受损组织释放的多种自身蛋白，包括几种热休克蛋白。膜相关C型凝集素受体（CLRs）识别免疫系统宿主细胞或特定组织上表达的聚糖结构，识别后可实现DCs与其他免疫或组织细胞之间的细胞相互作用。此外，CLRs可作为PRRs发挥作用。与TLRs不同，CLRs识别病原体上存在的碳水化合物结构。因此，将病原体上的聚糖结构修饰成模拟宿主聚糖的结构，可改变CLR相互作用，进而改变DC诱导的极化。在本综述中，我们将详细讨论抗原的特定糖基化如何决定由DCs上的CLRs介导的先天和适应性相互作用，以及这如何平衡免疫激活和DC功能的抑制。
