Chicken meat allergy (ChMA) has an estimated incidence of 0.6%–5%.¹ Symptoms range from mild oral syndrome to systemic reactions. Individual sensitization profiles remain poorly understood. The objective was to exhaustively and individually explore the clinical parameters (Table 1) and the IgE repertoire of five children (P1 to P5, 6–12 years old) with primary ChMA, without egg allergy, in order to compare clinical and IgE sensitization profiles. IgE repertoires were evaluated using multi-allergen chip (ALEX2©), dotline immunoassay on selected purified proteins, allergomic analysis, that is, two-dimensional (2D) gel electrophoresis of cooked chicken breast meat extract followed by IgE immunoblot (Figure 1A; Figure S1) and identification of allergens by liquid chromatography (LC) and mass spectrometry (MS) (see Methods in Data S1). Patients developed ChMA as the result of a break in tolerance. The skin prick test (SPT) and oral food challenge (OFC) were positive using chicken breast meat, poached and grilled. As depicted in 1D and 2D western blots (WB) (Figure 1D; Figure S1), profile complexity was low for P1 and P2, high for P4 and P5, and intermediate for P3. Proteins present in 30 excised gel spots matching 2D IgE-reactivities were identified by LC/MS/MS analysis (Figure S1). Out of 95 different proteins identified, 25 were considered to be the most relevant allergen candidates (Figure 1B) (see explanations in Data S1). Nine proteins corresponded to known allergens. Gal d 3, an allergen of mainly, but not only, egg white, is restricted to P2 and P3 and hemoglobin to P4 and P5. Gal d 7, 9, 10 and triose phosphate isomerase are potential allergens for P2, P3, P4 and P5. Gal d 5, also described in egg and chicken meat, is recognized by P5 only and Gal d tropomyosin by P4 only. Gal d 7 was found for all patients in WB and also in a dot/line immunoassay (Figure 1C), in agreement with its major characteristic.² IgE reactivity to parvalbumin, not explored in 2D WB because the protein is not present in chicken breast,³ was shown to be recognized by five patients by the dot/line immunoassay. Ten chicken candidate allergens already described as allergens in other animal sources (fish, crustaceans, cattle, worms, mites, and insects) were identified, such as troponin and cofilin-2, candidate allergens for all five patients. Patients P3 and P4 are allergic to other fowl (turkey and duck) and P3 is allergic to tuna fish, likely because of reported IgE cross-reactivities between known allergen families such as parvalbumin or myosin light chain,^2-5 but also other uncharacterized allergens. Some of these, mainly muscle proteins, are proposed as candidate allergens. As these proteins are part of large protein complexes, they might be processed together leading to a joint/synergistic Th2 sensitization. The ALEX2© multiplex assay (Table 1) detected reactivities to fish parvalbumin, probably as a consequence of IgE cross-reactivity not systematically related to allergy-induced symptoms. Finally, six additional putative IgE reactive proteins, not reported in animal food allergies, were found and some of them, like ATP synthase, malate dehydrogenase, and phosphoglycerate kinase, include allergens in plants and molds exhibiting more than 50% sequence identity with chicken orthologs. Chicken allergens with potential cross-reactivity with fish or crustacean are mentioned in Figure 1B either because they were reported cross-reactive in literature^{1, 6} or because they share more than 60% sequence identity (Uniprot Blast and Align). Allergens and patient overlaps are represented in a Venn diagram (Figure S2) and location of candidate allergens is shown on 1D WB (Figure 1D).

In conclusion, the allergomic study, performed with the sera from five ChMA children, showed highly diversified sensitization profiles with no correlation with clinical severity evaluated by symptoms, SPT, sIgE, OFC results, and potential cross-reactivities. The 25 candidate allergens pointed out pave the way for the identification of additional clinically relevant allergens as an approach to patient endotyping and stratification.

鸡肉过敏 (ChMA) 的发病率估计为 0.6%–5%。¹症状范围从轻微的口腔综合征到全身反应。个人的敏感性概况仍然知之甚少。目的是详尽、单独地探索 5 名患有原发性 ChMA、无鸡蛋过敏的儿童（P1 至 P5，6-12 岁）的临床参数（表 1）和 IgE 谱，以便比较临床和 IgE 致敏情况。使用多过敏原芯片 (ALEX2©)、对选定的纯化蛋白质进行点线免疫分析、过敏分析（即对煮熟的鸡胸肉提取物进行二维 (2D) 凝胶电泳，然后进行 IgE 免疫印迹）来评估 IgE 库（图 1A；图 1A；图 1A） S1) 以及通过液相色谱 (LC) 和质谱 (MS) 鉴定过敏原（参见数据 S1 中的方法）。患者因耐受性中断而出现 ChMA。使用水煮和烧烤的鸡胸肉进行的皮肤点刺试验（SPT）和口服食物挑战（OFC）呈阳性。如 1D 和 2D 蛋白质印迹 (WB) 所示（图 1D；图 S1），P1 和 P2 的谱复杂性较低，P4 和 P5 的谱复杂性较高，P3 的谱复杂性中等。通过 LC/MS/MS 分析鉴定了 30 个与 2D IgE 反应性匹配的切除凝胶点中存在的蛋白质（图 S1）。在确定的 95 种不同蛋白质中，有 25 种被认为是最相关的候选过敏原（图 1B）（参见数据 S1 中的解释）。九种蛋白质对应于已知的过敏原。 Gal d 3 是一种主要（但不仅限于）蛋清的过敏原，仅限于 P2 和 P3，血红蛋白仅限于 P4 和 P5。 Gal d 7、9、10 和磷酸丙糖异构酶是 P2、P3、P4 和 P5 的潜在过敏原。 Gal d 5（也存在于鸡蛋和鸡肉中）仅被 P5 识别，Gal d 原肌球蛋白仅被 P4 识别。在 WB 和点/线免疫测定中（图 1C），所有患者均发现了 Gal d 7，与其主要特征一致。² IgE 对小清蛋白的反应性，未在 2D WB 中进行探索，因为鸡胸肉中不存在该蛋白质，³已被 5 名患者通过点/线免疫测定法识别。已鉴定出 10 种鸡候选过敏原，这些过敏原已被描述为其他动物来源（鱼、甲壳类动物、牛、蠕虫、螨虫和昆虫）中的过敏原，例如肌钙蛋白和丝切蛋白-2，它们是所有 5 名患者的候选过敏原。患者 P3 和 P4 对其他家禽（火鸡和鸭）过敏，P3 对金枪鱼过敏，可能是因为已知过敏原家族（如小清蛋白或肌球蛋白轻链）之间报告的 IgE 交叉反应，^2-5还有其他未知的过敏原。其中一些，主要是肌肉蛋白，被提议作为候选过敏原。由于这些蛋白质是大型蛋白质复合物的一部分，因此它们可能一起加工，导致联合/协同 Th2 致敏。 ALEX2©多重检测（表1）检测到鱼小白蛋白的反应性，可能是由于IgE交叉反应性与过敏引起的症状没有系统相关。最后，还发现了六种其他推定的 IgE 反应蛋白，这些蛋白在动物性食品过敏中未曾报道，其中一些蛋白，如 ATP 合酶、苹果酸脱氢酶和磷酸甘油酸激酶，包括植物和霉菌中的过敏原，与鸡肉直系同源物具有超过 50% 的序列同一性。图 1B 中提到了与鱼类或甲壳类动物具有潜在交叉反应性的鸡肉过敏原，这要么是因为文献^1、6中报道了它们具有交叉反应性，要么是因为它们具有超过 60% 的序列同一性（Uniprot Blast 和 Align）。过敏原和患者重叠以维恩图表示（图 S2），候选过敏原的位置显示在 1D WB 上（图 1D）。

总之，使用 5 名 ChMA 儿童血清进行的过敏学研究显示，致敏情况高度多样化，与通过症状、SPT、sIgE、OFC 结果和潜在交叉反应评估的临床严重程度无关。 25 种候选过敏原指出，为识别其他临床相关过敏原作为患者内分型和分层的方法铺平了道路。