Sialic acid-binding immunoglobulin-type lectins (Siglecs) are immunomodulatory receptors that are regulated by their glycan ligands. A growing connection between Siglecs and human disease motivates improved methods to detect Siglec ligands. Here, we describe a new versatile set of Siglec-Fc proteins for glycan ligand detection. Enhanced sensitivity and selectivity are enabled through multimerization and avoiding Fc receptors, respectively. Using these Siglec-Fc proteins, Siglec ligands were systemically profiled on healthy and cancerous cells and tissues, revealing many unique patterns. Additional features enable the production of small, homogenous Siglec fragments and development of a quantitative ligand-binding mass spectrometry assay. Using this assay, the ligand specificities of several Siglecs were clarified. For CD33, we demonstrate that it recognizes both α2-3 and α2-6 sialosides in solution and on cells, which has implications for its link to Alzheimer's disease susceptibility. These soluble Siglecs reveal the abundance of their glycan ligands on host cells as self-associated molecular patterns.

中文翻译：

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多功能可溶性Siglec支架，用于糖配体的灵敏和定量检测

结合唾液酸的免疫球蛋白型凝集素（Siglecs）是受其聚糖配体调节的免疫调节受体。Siglecs与人类疾病之间日益紧密的联系促使人们改进了检测Siglec配体的方法。在这里，我们描述了一套用于聚糖配体检测的新型多功能Siglec-Fc蛋白。分别通过多聚和避免Fc受体可以提高灵敏度和选择性。使用这些Siglec-Fc蛋白，Siglec配体在健康和癌细胞及组织上进行了系统分析，从而揭示了许多独特的模式。附加功能使小而均匀的Siglec片段的产生和定量配体结合质谱分析的发展成为可能。使用该测定法，阐明了几种Siglecs的配体特异性。对于CD33，我们证明它可以识别溶液中和细胞上的α2-3和α2-6唾液酸唾液酸，这与其与阿尔茨海默氏病易感性有关。这些可溶的Siglecs揭示了宿主细胞上其聚糖配体的丰富性（作为自相关分子模式）。