Pastorello E A, Pravettoni V, Farioli L, Ispano M, Fortunato D, Monza M, Giuffrida M G, Rivolta F, Scibola E, Ansaloni R, Incorvaia C, Conti A, Ortolani C
Allergy Center, Third Division of General Medicine, Ospedale Maggiore Istituto di Ricerca e Cura a Carattere Scientifico, Milan, Italy.
J Allergy Clin Immunol. 1999 Nov;104(5):1099-106. doi: 10.1016/s0091-6749(99)70095-3.
Allergy to apple is commonly associated with birch pollinosis because the two share homologous allergens. However, some patients have apple allergy but no birch pollinosis, suggesting that there are allergens that do not cross-react with birch.
The aim of the study was to evaluate the IgE reactivity pattern to an apple extract in subjects with allergic reactions to apple, with and without birch hay fever.
Forty-three patients with oral allergy syndrome for apple and positive open food challenge, skin prick test, and serum specific IgE antibodies to apple were admitted to the study. Thirty-two had birch pollinosis (documented by specific IgE for birch) and 11 were not allergic to birch. The IgE reactivity pattern to apple extract was identified by SDS-PAGE and immunoblotting. The consistent allergen, a 9-kd protein, was then purified by HPLC and characterized by periodic acid-Schiff staining, isoelectric point, and N-terminal amino acid sequencing.
The sera from 28% of patients allergic to apple with birch pollinosis, but from all patients allergic only to apple, recognized the 9-kd protein. This protein has an isoelectric point of 7.5 and is not glycosylated. Determination of its partial amino acid sequence showed that it belongs to the family of lipid transfer proteins, which act as major allergens in Prunoideae fruits.
These results indicate that a lipid transfer protein is an important allergen in patients allergic to apple but not to birch pollen. The prevalent IgE reactivity to this allergen in subjects with no birch pollinosis and the physicochemical characteristics of this protein suggest that sensitization may occur through the oral route.
对苹果过敏通常与桦树花粉症相关，因为二者存在同源过敏原。然而，一些患者仅有苹果过敏而无桦树花粉症，这表明存在与桦树不发生交叉反应的过敏原。
本研究旨在评估对苹果有过敏反应的患者（无论有无桦树花粉症）血清中针对苹果提取物的IgE反应模式。
43例因苹果导致口腔过敏综合征且开放性食物激发试验、皮肤点刺试验及血清苹果特异性IgE抗体均呈阳性的患者纳入研究。其中32例有桦树花粉症（通过桦树特异性IgE证实），11例对桦树不过敏。通过SDS-PAGE和免疫印迹法确定血清对苹果提取物的IgE反应模式。然后，通过HPLC纯化出一种一致的过敏原——9-kD蛋白，并通过过碘酸-希夫染色、等电点及N端氨基酸测序对其进行鉴定。
28%对苹果过敏且患有桦树花粉症的患者血清以及所有仅对苹果过敏的患者血清均能识别该9-kD蛋白。该蛋白等电点为7.5，无糖基化修饰。对其部分氨基酸序列的测定表明，它属于脂质转移蛋白家族，该家族蛋白是李属果实中的主要过敏原。
这些结果表明，脂质转移蛋白是对苹果过敏但对桦树花粉不过敏患者的一种重要过敏原。在无桦树花粉症的患者中，该过敏原普遍存在IgE反应性，且该蛋白的理化特性提示其致敏可能通过口服途径发生。
