Activation of invariant natural killer T lymphocytes (iNKT cells) by α-galactosylceramide (α-GC) elicits a range of pro-inflammatory or anti-inflammatory immune responses. We report the synthesis and characterization of a series of α-GC analogues with acyl chains of varying length and a terminal benzophenone. These bound efficiently to the glycolipid antigen presenting protein CD1d, and upon photoactivation formed stable CD1d-glycolipid covalent conjugates. Conjugates of benzophenone α-GCs with soluble or cell-bound CD1d proteins retained potent iNKT cell activating properties, with biologic effects that were modulated by acyl chain length and the resulting affinities of conjugates for iNKT cell antigen receptors. Analysis by mass spectrometry identified a unique covalent attachment site for the glycolipid ligands in the hydrophobic ligand binding pocket of CD1d. The creation of covalent conjugates of CD1d with α-GC provides a new tool for probing the biology of glycolipid antigen presentation, as well as opportunities for developing effective immunotherapeutics.

中文翻译：

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光活化糖脂抗原与CD1d产生稳定的共轭物，用于不变的自然杀伤性T细胞活化

α-半乳糖苷神经酰胺（α-GC）激活不变的自然杀伤性T淋巴细胞（iNKT细胞）引发了一系列促炎性或抗炎性免疫反应。我们报告了一系列不同长度的酰基链和末端二苯甲酮的α-GC类似物的合成和表征。这些与糖脂抗原呈递蛋白CD1d有效结合，并在光激活后形成稳定的CD1d-糖脂共价结合物。二苯甲酮α-GC与可溶性或细胞结合CD1d蛋白的结合物保留了有效的iNKT细胞活化特性，其生物学效应受酰基链长度和结合物对iNKT细胞抗原受体的亲和力的调节。质谱分析确定了CD1d疏水配体结合口袋中糖脂配体的独特共价连接位点。CD1d与α-GC的共价结合物的创建为探测糖脂抗原呈递的生物学提供了新的工具，也为开发有效的免疫疗法提供了机会。