Wal J M
Laboratoire Associé INRA-CEA d'lmmuno-Allergie Alimentaire, DRM-SPl Bät. 136 CEA de Saclay, 91191 Gif sur Yvette, France.
Allergy. 2001;56 Suppl 67:35-8.
Proteins (CMP) involved in milk allergy are numerous and heterogeneous, with very few structural or functional common features. This heterogeneity is complicated by their genetic polymorphism, resulting in several variants for each protein. These variants are characterized by point substitutions of amino acids or by deletions of peptide fragments of varying size or by post-translational modifications such as phosphorylation or glycosylation. All of these modifications may affect allergenicity. No common molecular structure can be associated with allergenicity, although some homologous regions such as casein phospho-peptides can explain an IgE cross-reactivity. Three-dimensional structure is an important feature in CMP allergenicity but denatured and linear epitopes are also involved. Epitopes are numerous and widely spread along the CMP molecule. They may be located in hydrophobic parts of the molecule where they are inaccessible for IgE antibodies in the native conformation of the protein but become bioavailable after digestive processes. Peptides as short as ca. 12-14 amino acid residues may account for a significant part of the allergenicity of the whole molecule, which justifies the need to be careful before proposing any CMP hydrolysate for highly allergenic children.
参与牛奶过敏的蛋白质（酪蛋白）种类繁多且具有异质性，结构或功能上的共同特征很少。它们的基因多态性使这种异质性更为复杂，导致每种蛋白质都有几种变体。这些变体的特征是氨基酸的点突变、不同大小肽片段的缺失或翻译后修饰，如磷酸化或糖基化。所有这些修饰都可能影响致敏性。尽管一些同源区域（如酪蛋白磷酸肽）可以解释IgE交叉反应，但没有共同的分子结构与致敏性相关。三维结构是酪蛋白致敏性的一个重要特征，但变性和线性表位也起作用。表位众多且广泛分布于酪蛋白分子中。它们可能位于分子的疏水部分，在蛋白质的天然构象中，IgE抗体无法接近这些区域，但在消化过程后会变得可被利用。短至约12 - 14个氨基酸残基的肽段可能占整个分子致敏性的很大一部分，这证明在为高度过敏儿童推荐任何酪蛋白水解物之前需要谨慎。
