Department of Infection and Immunity, Luxembourg Institute of Health (LIH), Esch-sur-Alzette, Luxembourg; Faculty of Science, Technology and Medicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg.
Department of Dermatology, Faculty of Medicine, Eberhard Karls University Tübingen, Tübingen, Germany.
J Allergy Clin Immunol. 2022 Aug;150(2):396-405.e11. doi: 10.1016/j.jaci.2022.02.030. Epub 2022 Apr 19.
The α-Gal syndrome is associated with the presence of IgE directed to the carbohydrate galactose-α-1,3-galactose (α-Gal) and is characterized by a delayed allergic reaction occurring 2 to 6 hours after ingestion of mammalian meat. On the basis of their slow digestion and processing kinetics, α-Gal-carrying glycolipids have been proposed as the main trigger of the delayed reaction.
We analyzed and compared the in vitro allergenicity of α-Gal-carrying glycoproteins and glycolipids from natural food sources.
Proteins and lipids were extracted from pork kidney (PK), beef, and chicken. Glycolipids were purified from rabbit erythrocytes. The presence of α-Gal and IgE binding of α-Gal-allergic patient sera (n = 39) was assessed by thin-layer chromatography as well as by direct and inhibition enzyme-linked immunosorbent assay. The in vitro allergenicity of glycoproteins and glycolipids from different meat extracts was determined by basophil activation test. Glycoprotein stability was evaluated by simulated gastric and intestinal digestion assays.
α-Gal was detected on glycolipids of PK and beef. Patient IgE antibodies recognized α-Gal bound to glycoproteins and glycolipids, although binding to glycoproteins was more potent. Rabbit glycolipids were able to strongly activate patient basophils, whereas lipid extracts from PK and beef were also found to trigger basophil activation, but at a lower capacity compared to the respective protein extracts. Simulated gastric digestion assays of PK showed a high stability of α-Gal-carrying proteins in PK.
Both α-Gal-carrying glycoproteins and glycolipids are able to strongly activate patient basophils. In PK and beef, α-Gal epitopes seem to be less abundant on glycolipids than on glycoproteins, suggesting a major role of glycoproteins in delayed anaphylaxis upon consumption of these food sources.
α-半乳糖综合征与针对碳水化合物半乳糖-α-1,3-半乳糖（α-Gal）的 IgE 有关，其特征是在摄入哺乳动物肉后 2 至 6 小时发生延迟过敏反应。基于其缓慢的消化和处理动力学，携带α-Gal 的糖脂已被提议为延迟反应的主要触发因素。
我们分析和比较了天然食物来源中携带α-Gal 的糖蛋白和糖脂的体外变应原性。
从猪肾（PK）、牛肉和鸡肉中提取蛋白质和脂质。从兔红细胞中纯化糖脂。通过薄层层析以及直接和抑制酶联免疫吸附试验评估α-Gal 的存在和α-Gal 过敏患者血清（n=39）的 IgE 结合。通过嗜碱性粒细胞活化试验测定来自不同肉提取物的糖蛋白和糖脂的体外变应原性。通过模拟胃和肠消化测定评估糖蛋白的稳定性。
PK 和牛肉的糖脂上检测到α-Gal。患者 IgE 抗体识别与糖蛋白和糖脂结合的α-Gal，尽管与糖蛋白的结合更有效。兔糖脂能够强烈激活患者嗜碱性粒细胞，而 PK 和牛肉的脂质提取物也被发现能够触发嗜碱性粒细胞活化，但与各自的蛋白提取物相比，其能力较低。PK 的模拟胃消化试验显示 PK 中携带α-Gal 的蛋白质具有很高的稳定性。
携带α-Gal 的糖蛋白和糖脂都能够强烈激活患者的嗜碱性粒细胞。在 PK 和牛肉中，与糖蛋白相比，α-Gal 表位在糖脂上似乎不那么丰富，这表明在摄入这些食物来源时，糖蛋白在延迟过敏反应中起主要作用。
