Cudowska B, Kaczmarski M, Restani P
III Department of Paediatrics, Medical University of Białystok, Poland.
Rocz Akad Med Bialymst. 2005;50:268-73.
The scientific experiments with new immunological methods (immunoblotting, RAST inhibition) and isolation of recombinant allergens suggest structural similarities in the allergenic components responsible for cross-reactions. Immunochemical and molecular biology studies indicate that epitopes of major allergen (Bet v 1, Mal d 1) contain more IgE binding epitopes than minor allergens (Bet v 2, Mal d 2), what explained clinical importance of major birch and apple allergens, but it is individual. The important role in cross-reactivity play also proteins with low molecular weight; a potentially dangerous allergen is lipid transfer protein (LTP) inducing severe systemic reactions in allergic subjects. The recent studies indicate that the IgE cross-reactivity patterns and the clinical relevance is still not clear and that only some of patients with confirmed IgE cross allergy to Bet v 1 and Mal d 1 demonstrated clinical symptoms after ingesting of apple. The aim of study was to establish the pattern of cross-reactivity between major (Bet v 1) and minor (Bet v 2) birch pollen allergens and apple proteins in children allergic to birch using recombinant allergens and immunoblotting method.
The prospective study were carried out on the group of 13 children aged 4-16 years, referred to the IIIrd Department of Paediatrics in Białystok and outpatient clinic with clinical symptoms of food and inhalant allergy. Inclusion criteria to the study were: allergy to birch pollen recombinant allergens and apple, confirmed by presence of specific IgE in the sera of patients. The allergens from peel and pulp of apple and birch were separated and loaded onto the polyacrylamide electrophoretic gel and than transferred to membranes by Western blotting. Antigen-IgE complex was detected using goat anti-human IgE antibodies labelled with alkaline phosphatase.
Only few sera presented strong reactions in immunoblotting to birch pollen proteins with a molecular weight of 17-18 kDa, corresponding to the main birch allergen Bet v 1. Most of sera having positive reaction vs Bet v 1 showed cross-reactivity with Mal d 1. All sera recognized specifically the main allergen of apple peel Mal d 3 with molecular weight < 10 kDa (Lipid Transfer Protein).
Immunoblotting method allows to verification of cross-reactivity recognized by presence of specific IgE. The nature of proteins responsible for sensitization can influence the spectrum of offending foods and the clinical features of allergic reactions.
采用新的免疫方法（免疫印迹法、RAST抑制法）进行的科学实验以及重组变应原的分离表明，引起交叉反应的变应原成分在结构上具有相似性。免疫化学和分子生物学研究表明，主要变应原（Bet v 1、Mal d 1）的表位比次要变应原（Bet v 2、Mal d 2）含有更多的IgE结合表位，这解释了主要桦树和苹果变应原的临床重要性，但存在个体差异。低分子量蛋白质在交叉反应中也起重要作用；一种潜在危险的变应原是脂质转移蛋白（LTP），可在过敏个体中诱发严重的全身反应。最近的研究表明，IgE交叉反应模式和临床相关性仍不明确，只有一些已证实对Bet v 1和Mal d 1存在IgE交叉过敏的患者在摄入苹果后出现临床症状。本研究的目的是利用重组变应原和免疫印迹法，确定对桦树过敏的儿童中主要（Bet v 1）和次要（Bet v 2）桦树花粉变应原与苹果蛋白之间的交叉反应模式。
对13名年龄在4至16岁之间、因食物和吸入性过敏临床症状转诊至比亚韦斯托克儿科第三科和门诊的儿童进行了前瞻性研究。该研究的纳入标准为：患者血清中存在特异性IgE，证实对桦树花粉重组变应原和苹果过敏。分离苹果和桦树果皮及果肉中的变应原，加载到聚丙烯酰胺电泳凝胶上，然后通过蛋白质印迹法转移到膜上。使用碱性磷酸酶标记的山羊抗人IgE抗体检测抗原-IgE复合物。
只有少数血清在免疫印迹中对分子量为17 - 18 kDa的桦树花粉蛋白呈现强反应，该蛋白对应主要桦树变应原Bet v 1。大多数对Bet v 1呈阳性反应的血清与Mal d 1表现出交叉反应。所有血清均特异性识别苹果果皮主要变应原Mal d 3，其分子量< 10 kDa（脂质转移蛋白）。
免疫印迹法可通过特异性IgE的存在来验证交叉反应。引起致敏的蛋白质的性质可影响引发过敏反应的食物范围和过敏反应的临床特征。
