Sánchez-Ruano L, Fernández-Lozano C, Ferrer M, Gómez F, de la Hoz B, Martínez-Botas J, Goikoetxea M J
Allergy Department, Hospital Universitario Ramón y Cajal, Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, Spain.
Servicio de Bioquímica-Investigación, Hospital Universitario Ramón y Cajal - Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, Spain.
Front Allergy. 2022 Jul 22;3:896617. doi: 10.3389/falgy.2022.896617. eCollection 2022.
Peanut-allergic patients from the Mediterranean region are predominantly sensitized to the lipid transfer protein (LTP) Ara h 9, and the peach LTP Pru p 3 seems to be the primary sensitizer. However, LTP sensitization in peanut allergy is not a predictive marker for clinically relevant symptoms.
We aimed to identify sequential epitopes of IgE and IgG4 from Pru p 3 and Ara h 9 in peach-allergic patients sensitized to peanuts. We also sought to determine the differences in IgE and IgG4 binding between patients who had developed peanut allergy and those tolerating peanuts.
A total of 46 peach-allergic patients sensitized to peanuts were selected. A total of 35 patients were allergic to peanuts (peanut-allergic group) and 11 were tolerant to peanuts (peanut-tolerant group). We measured sIgE and sIgG4 in peanut, peach, and their recombinant allergen (Ara h 1, Ara h 2, Ara h 3, Ara h 8, and Ara h 9) with fluorescence enzyme immunoassay. We examined the IgE and IgG4 binding to sequential epitopes using a peptide microarray corresponding to linear sequences of the LTPs Ara h 9 and Pru p 3 with a library of overlapping peptides with a length of 20 amino acids (aa) and an offset of 3 aa.
The frequency and the intensity of IgE recognition of Ara h 9 and Pru p 3 peptides were higher in the peanut-tolerant group than in the peanut-allergic group. We found four Ara h 9 peptides (p4, p14, p21, and p25) and four Pru p 3 peptides (p1, p3, p21, and p24) with a significantly elevated IgE recognition in peanut-tolerant patients. Only one peptide of Ara h 9 (p4) recognized by IgG4 was significantly elevated in the peanut-tolerant group. The IgG4/IgE ratio of Ara h 9 peptide 4 was significantly higher in peanut-tolerant patients than in peanut-allergic patients, while no significant differences were observed in the IgG4/IgE ratio of this peptide in Pru p 3.
Although we found significant differences in IgE and IgG4 recognition of Ara h 9 and Pru p 3 between peanut-tolerant and peanut-allergic patients (all of whom were allergic to peach), polyclonal IgE peptide recognition of both LTPs was observed in peach-allergic patients tolerating peanuts. However, the IgG4 blocking antibodies against Ara h 9 peptide 4 could provide an explanation for the absence of clinical reactivity in peanut-tolerant peach-allergic patients. Further studies are needed to validate the usefulness of IgG4 antibodies against Ara h 9 peptide 4 for peanut allergy diagnosis.
地中海地区的花生过敏患者主要对脂质转移蛋白（LTP）Ara h 9致敏，而桃LTP Pru p 3似乎是主要致敏原。然而，花生过敏中的LTP致敏并非临床相关症状的预测标志物。
我们旨在鉴定对花生致敏的桃过敏患者中来自Pru p 3和Ara h 9的IgE和IgG4的连续表位。我们还试图确定已发生花生过敏的患者与耐受花生的患者之间IgE和IgG4结合的差异。
共选择了46名对花生致敏的桃过敏患者。其中35名患者对花生过敏（花生过敏组），11名患者耐受花生（花生耐受组）。我们用荧光酶免疫测定法检测花生、桃及其重组变应原（Ara h 1、Ara h 2、Ara h 3、Ara h 8和Ara h 9）中的特异性IgE（sIgE）和特异性IgG4（sIgG4）。我们使用与LTPs Ara h 9和Pru p 3的线性序列相对应的肽微阵列，以及一个由长度为20个氨基酸（aa）且偏移量为3个aa的重叠肽库，来检测IgE和IgG4与连续表位的结合。
花生耐受组中Ara h 9和Pru p 3肽段的IgE识别频率和强度高于花生过敏组。我们发现花生耐受患者中有4个Ara h 9肽段（p4、p14、p21和p25）和4个Pru p 3肽段（p1、p3、p21和p24）的IgE识别显著升高。花生耐受组中仅被IgG4识别的一个Ara h 9肽段（p4）显著升高。花生耐受患者中Ara h 9肽段4的IgG4/IgE比值显著高于花生过敏患者，而该肽段在Pru p 3中的IgG4/IgE比值未观察到显著差异。
虽然我们发现花生耐受和花生过敏患者（均对桃过敏）之间在Ara h 9和Pru p 3的IgE和IgG4识别上存在显著差异，但在耐受花生的桃过敏患者中观察到了对两种LTP的多克隆IgE肽段识别。然而，针对Ara h 9肽段4的IgG4阻断抗体可以解释花生耐受的桃过敏患者缺乏临床反应性的原因。需要进一步研究来验证针对Ara h 9肽段4的IgG4抗体对花生过敏诊断的有用性。
