Comparative Medicine, Messerli Research Institute, University of Veterinary Medicine Vienna, Vienna, Medical University of Vienna and University of Vienna, Austria.
Mol Nutr Food Res. 2013 Mar;57(3):536-44. doi: 10.1002/mnfr.201200612. Epub 2013 Jan 24.
Patients with persistent egg allergy have more immunoglobulin E (IgE) against sequential than conformational epitopes of ovomucoid (OVO). Here, we aimed to identify compounds capable to render sequential epitopes in egg.
Glutathione was used for in vitro reduction of OVO and circular dichroism analyses were performed. Glutathione reduced OVO in a concentration-dependent manner. Egg white was analyzed for reduced proteins with a thiol probe and by MALDI-TOF/TOF. In unprocessed total egg white, several reduced proteins were detected by the thiol probe, among them reduced ovalbumin could be confirmed with MS analyses. Egg-allergics or sensitized controls were tested serologically (n = 19) for IgE against native and reduced OVO and in skin prick tests (n = 9). More patients had IgE against reduced than native OVO in Western blots. In skin prick test, five out of seven persistent egg-allergics and none of the controls reacted with reduced OVO.
Reduced egg proteins are present in natural egg white. Glutathione, which is present in egg and furthermore is used as texture-improving additive in processed food, is capable of reducing OVO. Patients with persistent egg allergy reacted rather to reduce the native OVO. Hence, our data indicate that reduction is a novel natural and processing-associated principle, which contributes to the allergenicity of food.
对卵清蛋白（OVA）连续表位具有更多免疫球蛋白 E（IgE）的持续性鸡蛋过敏患者，比构象表位更具有免疫球蛋白 E。在此，我们旨在确定能够使鸡蛋中的连续表位失活的化合物。
使用谷胱甘肽进行卵清蛋白的体外还原，并进行圆二色性分析。谷胱甘肽以浓度依赖性方式还原 OVO。使用巯基探针和 MALDI-TOF/TOF 分析蛋清中的还原蛋白。在未经处理的全蛋清中，巯基探针检测到几种还原蛋白，其中还原卵白蛋白可以通过 MS 分析得到证实。对鸡蛋过敏者或致敏对照者进行血清学检测（n=19），以检测针对天然和还原卵清蛋白的 IgE，并进行皮肤点刺试验（n=9）。在 Western blot 中，更多的患者对还原卵清蛋白的 IgE 反应阳性，而不是对天然卵清蛋白的 IgE 反应阳性。在皮肤点刺试验中，7 名持续性鸡蛋过敏者中有 5 名对还原卵清蛋白有反应，而对照组无一例有反应。
还原的鸡蛋蛋白存在于天然蛋清中。谷胱甘肽存在于鸡蛋中，并且在加工食品中用作改善质地的添加剂，它能够还原 OVO。持续性鸡蛋过敏患者对还原的天然 OVO 反应更为强烈。因此，我们的数据表明，还原是一种新的天然和加工相关的原理，它有助于食物的致敏性。
