Restani P, Velonà T, Plebani A, Ugazio A G, Poiesi C, Muraro A, Galli C L
Laboratory of Toxicology, University of Milan, Italy.
Clin Exp Allergy. 1995 Jul;25(7):651-8. doi: 10.1111/j.1365-2222.1995.tb01113.x.
Extensively hydrolysed protein formulas are widely used as an alternative diet for children with cow's milk allergy. Partially hydrolysed protein formulas have been noted in some studies as useful in the prevention of allergy in infants at high risk of atopy. Although normally well tolerated, these 'hypoallergenic' products have been reported to cause serious immunological reactions in very sensitive subjects.
Starting from these considerations, we studied some commercial hydrolysed formulas in search of biological data supporting the observed clinical reactions.
We set up an electrophoretic method sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) which allowed us to study the molecular weight of peptides contained in hydrolysed products. Then, using the immunoblotting technique we evaluated the reactivity of circulating IgE (from serum of children allergic to cow's milk proteins) with the residual intact proteins and with the peptides present in these formulas.
Both group of milk proteins (caseins and whey proteins) were important allergens for children included in this study. The presence of high-molecular polypeptides was shown in partial hydrolysed formulas as such and in extensive hydrolysed products after protein enrichment by trichloroacetic acid (TCA) precipitation. Intact residual proteins were mainly responsible for the formation of IgE-antigen complexes observed in immunoblotting. More rarely, polypeptides of partial hydrolysed formulas were involved in immunological responses.
Both partial and extensive hydrolysed formulas could induce clinical reactions in very sensitive subjects. These responses are mainly associated with allergy to the small amounts of residual intact proteins.
深度水解蛋白配方奶粉被广泛用作牛奶过敏儿童的替代饮食。一些研究指出，部分水解蛋白配方奶粉对预防有特应性高风险的婴儿过敏有用。尽管这些“低敏”产品通常耐受性良好，但据报道，在非常敏感的个体中会引起严重的免疫反应。
基于这些考虑，我们研究了一些市售水解配方奶粉，以寻找支持所观察到的临床反应的生物学数据。
我们建立了一种电泳方法——十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE），该方法使我们能够研究水解产物中所含肽的分子量。然后，使用免疫印迹技术，我们评估了循环IgE（来自对牛奶蛋白过敏儿童的血清）与这些配方奶粉中残留的完整蛋白和肽的反应性。
两组乳蛋白（酪蛋白和乳清蛋白）都是本研究中儿童的重要过敏原。在部分水解配方奶粉中以及通过三氯乙酸（TCA）沉淀富集蛋白质后的深度水解产物中都显示出高分子量多肽的存在。完整的残留蛋白是免疫印迹中观察到的IgE-抗原复合物形成的主要原因。更罕见的是，部分水解配方奶粉中的多肽参与免疫反应。
部分水解和深度水解配方奶粉都可能在非常敏感的个体中引发临床反应。这些反应主要与对少量残留完整蛋白的过敏有关。
