Bernard Hervé, Hazebrouck Stéphane, Gaiani Nicolas, Adel-Patient Karine
Université Paris-Saclay, CEA, INRAE, Département Médicaments et Technologies pour la Santé, Service de Pharmacologie et d'Immunoanalyse, Laboratoire d'Immuno-Allergie Alimentaire, Gif-sur-Yvette, France.
Front Allergy. 2021 Sep 30;2:733875. doi: 10.3389/falgy.2021.733875. eCollection 2021.
Despite a high level of sequence identity between cow's, goat's, and sheep's milk (CM, GM, and SM, respectively) proteins, some patients tolerant to CM are allergic to GM and SM. In most cases, this specificity is due to the presence of IgE antibodies that bind only to caprine and ovine caseins. The patients may then develop severe allergic reactions after ingestion of CM products contaminated with low amounts of GM or SM. We thus aimed to develop an assay able to detect traces of caprine/ovine β-caseins in different food matrices, irrespective of the presence of the bovine homolog. We produced monoclonal antibodies (mAbs) specific to caprine caseins in mice tolerized to the bovine whole casein then sensitized to the caprine whole casein. In order to develop a two-site immunometric assay, we selected mAbs that could discriminate the caprine β-casein from its bovine homolog. Characteristics and performances of two tests were determined with various dairy products. Results were analyzed in relation with the IgE-immunoreactivity of the food matrices, thanks to sera from CM, GM/SM allergic patients. Our two-site immunometric assays demonstrated a high sensitivity with a detection limit of 1.6-3.2 ng/mL of caprine and ovine β-caseins. The tests were able to detect contaminations of GM in CM at the ppm level. Heat-treatment, ripening and coagulation processes, usually applied to dairy products that exhibit a very high IgE-immunoreactivity, did not impair the test sensitivity. These quantitative assays could then be useful for the risk assessment of food products potentially contaminated with GM and SM in order to prevent adverse reactions in patients specifically allergic to these milks.
尽管牛奶、羊奶和绵羊奶（分别为CM、GM和SM）中的蛋白质具有高度的序列同一性，但一些耐受CM的患者对GM和SM过敏。在大多数情况下，这种特异性是由于存在仅与山羊和绵羊酪蛋白结合的IgE抗体。这些患者在摄入被少量GM或SM污染的CM产品后可能会出现严重的过敏反应。因此，我们旨在开发一种检测方法，能够检测不同食品基质中痕量的山羊/绵羊β-酪蛋白，而不考虑牛同源物的存在。我们在对牛全酪蛋白耐受然后对山羊全酪蛋白致敏的小鼠中制备了对山羊酪蛋白特异的单克隆抗体（mAb）。为了开发一种双位点免疫测定法，我们选择了能够区分山羊β-酪蛋白与其牛同源物的mAb。用各种乳制品测定了两种检测方法的特性和性能。借助CM、GM/SM过敏患者的血清，将结果与食品基质的IgE免疫反应性相关联进行分析。我们的双位点免疫测定法显示出高灵敏度，山羊和绵羊β-酪蛋白的检测限为1.6 - 3.2 ng/mL。这些检测方法能够检测出CM中ppm水平的GM污染。通常应用于具有非常高IgE免疫反应性的乳制品的热处理、成熟和凝固过程，不会损害检测灵敏度。这些定量测定法可用于对可能被GM和SM污染的食品进行风险评估，以防止对这些牛奶特异过敏的患者出现不良反应。
