INRA, UR 496, Unité d'Immuno-Allergie Alimentaire, CEA de Saclay, Gif-sur-Yvette, France.
Mol Nutr Food Res. 2012 Oct;56(10):1532-40. doi: 10.1002/mnfr.201200229. Epub 2012 Sep 7.
Despite a sequence homology of 90% between bovine and caprine β-caseins (CN), IgE antibodies from patients allergic to goat's milk (GM), but tolerant to cow's milk (CM), recognize caprine β-CN without cross-reacting with bovine β-CN. We investigated this lack of cross-reactivity by evaluating the IgE-reactivity toward peptides isolated from plasmin hydolysates of bovine and caprine β-CN.
The IgE-binding capacity of plasmin-derived peptides was evaluated with sera from 10 CM-allergic patients and 12 GM-allergic/CM-tolerant patients. In CM-allergic patients, IgE reactivity of caprine fragments (f29-107) and (f108-207), but not (f1-28), was similar to that of the bovine counterparts. In contrast, all bovine fragments were poorly recognized by IgE antibodies from GM-allergic/CM-tolerant patients. The peptide (f29-107) was generally the most immunoreactive fragment of caprine β-CN. By using synthetic peptides, the immunodominant IgE-binding epitope recognized by most GM-allergic/CM-tolerant patients was located in the caprine domain 49-79.
The restricted specificity of the IgE response toward the caprine β-CN in GM-allergic/CM-tolerant patients is mainly directed against the domain 49-79, which differs from its bovine counterpart by only three amino acid substitutions.
尽管牛β-酪蛋白（CN）和山羊β-酪蛋白（CN）之间存在 90%的序列同源性，但对山羊奶（GM）过敏但能耐受牛奶（CM）的患者的 IgE 抗体能识别山羊β-CN，而不与牛β-CN 发生交叉反应。我们通过评估从牛和山羊β-CN 的纤溶酶水解产物中分离的肽的 IgE 反应性来研究这种缺乏交叉反应性的原因。
用 10 名 CM 过敏患者和 12 名 GM 过敏/CM 耐受患者的血清评估纤溶酶衍生肽的 IgE 结合能力。在 CM 过敏患者中，山羊片段（f29-107）和（f108-207）的 IgE 反应性与牛的相似，但（f1-28）则不然。相比之下，所有的牛片段都不能被 GM 过敏/CM 耐受患者的 IgE 抗体识别。该肽（f29-107）通常是山羊β-CN 最具免疫反应性的片段。通过使用合成肽，大多数 GM 过敏/CM 耐受患者识别的免疫显性 IgE 结合表位位于山羊结构域 49-79 内。
GM 过敏/CM 耐受患者对山羊β-CN 的 IgE 反应特异性主要针对其与牛的不同之处仅为三个氨基酸取代的结构域 49-79。
