Mayer Sabine, Raulf Marie-Kristin, Lepenies Bernd
Immunology Unit and Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine, Bünteweg 17, 30559, Hannover, Germany.
Institute for Parasitology, Center for Infection Medicine, University of Veterinary Medicine, Hannover, Germany.
Histochem Cell Biol. 2017 Feb;147(2):223-237. doi: 10.1007/s00418-016-1523-7. Epub 2016 Dec 20.
C-type lectins (CTLs) represent the most complex family of animal/human lectins that comprises 17 different groups. During evolution, CTLs have developed by diversification to cover a broad range of glycan ligands. However, ligand binding by CTLs is not necessarily restricted to glycans as some CTLs also bind to proteins, lipids, inorganic molecules, or ice crystals. CTLs share a common fold that harbors a Ca for contact to the sugar and about 18 invariant residues in a phylogenetically conserved pattern. In vertebrates, CTLs have numerous functions, including serum glycoprotein homeostasis, pathogen sensing, and the initiation of immune responses. Myeloid CTLs in innate immunity are mainly expressed by antigen-presenting cells and play a prominent role in the recognition of a variety of pathogens such as fungi, bacteria, viruses, and parasites. However, myeloid CTLs such as the macrophage inducible CTL (Mincle) or Clec-9a may also bind to self-antigens and thus contribute to immune homeostasis. While some CTLs induce pro-inflammatory responses and thereby lead to activation of adaptive immune responses, other CTLs act as inhibitory receptors and dampen cellular functions. Since CTLs are key players in pathogen recognition and innate immunity, targeting CTLs may be a promising strategy for cell-specific delivery of drugs or vaccine antigens and to modulate immune responses.
C型凝集素（CTLs）是动物/人类凝集素中最复杂的家族，由17个不同的组组成。在进化过程中，CTLs通过多样化发展，以覆盖广泛的聚糖配体。然而，CTLs与配体的结合并不一定局限于聚糖，因为一些CTLs也能与蛋白质、脂质、无机分子或冰晶结合。CTLs具有共同的折叠结构，其中含有一个与糖接触的钙离子，以及约18个以系统发育保守模式存在的不变残基。在脊椎动物中，CTLs具有多种功能，包括血清糖蛋白稳态、病原体感知和免疫反应的启动。先天性免疫中的髓系CTLs主要由抗原呈递细胞表达，在识别多种病原体（如真菌、细菌、病毒和寄生虫）中发挥重要作用。然而，髓系CTLs，如巨噬细胞诱导性CTL（Mincle）或Clec-9a，也可能与自身抗原结合，从而有助于免疫稳态。虽然一些CTLs诱导促炎反应，从而导致适应性免疫反应的激活，但其他CTLs作为抑制性受体，会抑制细胞功能。由于CTLs是病原体识别和先天性免疫的关键参与者，靶向CTLs可能是一种有前景的策略，用于细胞特异性递送药物或疫苗抗原以及调节免疫反应。
