Division of Allergology, Paul-Ehrlich-Institut, Langen, Germany.
Department of Biopolymers, University of Bayreuth, Bayreuth, Germany.
Clin Exp Allergy. 2017 May;47(5):693-703. doi: 10.1111/cea.12835. Epub 2016 Nov 28.
Allergen-specific immunotherapy (AIT) with birch pollen generates Bet v 1-specific immunoglobulin (Ig)G which blocks IgE-mediated hypersensitivity mechanisms. Whether IgG specific for Bet v 1a competes with IgE for identical epitopes or whether novel epitope specificities of IgG antibodies are developed is under debate.
We sought to analyze the epitope specificities of IgE and IgG antibodies from sera of patients who received AIT.
15 sera of patients (13/15 received AIT) with Bet v 1a-specific IgE and IgG were analyzed. The structural arrangements of recombinant (r)Bet v 1a and rBet v 1a , modified in five potential epitopes, were analyzed by circular dichroism and nuclear magnetic resonance spectroscopy. IgE binding to Bet v 1 was assessed by ELISA and mediator release assays. Competitive binding of monoclonal antibodies specific for Bet v 1a and serum IgE/IgG to rBet v 1a and serum antibody binding to a non-allergenic Bet v 1-type model protein presenting an individual epitope for IgE was analyzed in ELISA and western blot.
rBet v 1a had a Bet v 1a - similar secondary and tertiary structure. Monomeric dispersion of rBet v 1a was concentration and buffer-dependent. Up to 1500-fold increase in the EC for IgE-mediated mediator release induced by rBet v 1a was determined. The reduction of IgE and IgG binding to rBet v 1a was comparable in 67% (10/15) of sera. Bet v 1a-specific monoclonal antibodies inhibited binding of serum IgE and IgG to 66.1% and 64.9%, respectively. Serum IgE and IgG bound specifically to an individual epitope presented by our model protein in 33% (5/15) of sera.
Patients receiving AIT develop Bet v 1a-specific IgG which competes with IgE for partly identical or largely overlapping epitopes. The similarities of epitopes for IgE and IgG might stimulate the development of epitope-specific diagnostics and therapeutics.
桦树花粉过敏原特异性免疫治疗（AIT）会产生特异性 IgG，该 IgG 可阻断 IgE 介导的过敏反应机制。针对特异性 IgG 是与 IgE 竞争相同表位，还是会产生新的 IgG 抗体特异性表位仍存在争议。
我们旨在分析接受 AIT 的患者血清中 IgE 和 IgG 抗体的表位特异性。
分析了 15 例血清（13/15 例接受 AIT）中特异性针对 Bet v 1a 的 IgE 和 IgG。通过圆二色性和核磁共振光谱分析了重组（r）Bet v 1a 和 rBet v 1a 的结构排列，这两种物质在五个潜在的表位中进行了修饰。通过 ELISA 和介质释放试验评估了 IgE 与 Bet v 1 的结合。通过 ELISA 和 Western blot 分析了特异性针对 Bet v 1a 的单克隆抗体与 rBet v 1a 和血清 IgG/IgE 的竞争结合以及非变应原性 Bet v 1 型模型蛋白对 IgE 呈现的个体表位的血清抗体结合。
rBet v 1a 具有类似于 Bet v 1a 的二级和三级结构。rBet v 1a 的单体分散性取决于浓度和缓冲液。rBet v 1a 诱导的 IgE 介导的介质释放的 EC 增加了高达 1500 倍。在 67%（10/15）的血清中，rBet v 1a 的 IgE 和 IgG 结合减少了相同的比例。Bet v 1a 特异性单克隆抗体分别抑制了 66.1%和 64.9%的血清 IgE 和 IgG 结合。在 33%（5/15）的血清中，血清 IgE 和 IgG 特异性地结合了我们模型蛋白上呈现的单个表位。
接受 AIT 的患者会产生特异性 IgG，该 IgG 会与 IgE 竞争部分相同或大部分重叠的表位。针对 IgE 和 IgG 的表位相似可能会刺激开发针对表位的诊断和治疗方法。
