Role of Memory IgG B Cells in the Development of Tolerance in Food Allergy

只有一部分IgE介导的食物过敏患者在口服后产生临床耐受性。 免疫疗法（OIT），这已被归因于发展保护性，功能抑制性 抗体的然而，那些失去耐受性的人通常会出现过敏原的早期短暂增加- 特异性IgE以前，我们描述了在OIT早期诱导变应原特异性记忆B细胞， 这些特异性IgG B细胞可以通过顺序的类别转换作为IgE记忆库。因此，我们认为， 产生保护性IgG或IgA抗体的特异性IgG B细胞相对于致病性IgG或IgA抗体的相对贡献 IgE对OIT免疫耐受的发展至关重要。了解该B的贡献 细胞命运的决定可能会导致过敏性疾病的新的治疗方式的发展。 在OIT中，我们最近发表了嗜碱性粒细胞敏感性抑制是耐受性的生物标志物。 嗜碱性粒细胞的功能抑制而不是过敏原特异性IgG的大量水平与耐受性相关， 提示OIT诱导的抗体库可能与耐受性的发展高度相关。 我们已经开发了一种高度特异性的荧光多聚体来识别和表征过敏原特异性B细胞 为了确定这些B细胞的克隆贡献。利用这些工具，我们可以跟踪 从OIT诱导的记忆性IgG B细胞到血清后效应抗体的克隆进化来解释 特异性IgG B细胞的抗体进化如何影响OIT的临床结局。 基于这些发现，我们假设过敏原特异性记忆IgG B细胞可以引起 保护性或致病性抗体决定OIT后的长期耐受性。我们的方法 结合了抗原特异性B细胞的分离用于单细胞BCR测序、BCR库分析和 血清蛋白质组学分析了花生过敏原Ara h 2的血清抗体在整个过程中的克隆性 的OIT。我们在开展这项研究方面具有独特的优势，因为我们拥有来自 既往接受过OIT治疗的患者。我们将在以下具体目标中阐述我们的假设：（1） 评价持续耐受中保护性、功能抑制性过敏原特异性IgG的形成 OIT后;（2）评估OIT后顺序切换在公差损失中的作用。 我们预计，拟议的研究将阐明长期临床 OIT在克隆水平上对保护性和致病性抗体的有效性，突出了OIT的关键作用。 记忆过敏原特异性IgG B细胞，并导致治疗食物过敏的新策略。的 开发技术来跟踪抗原特异性B细胞的命运，使用BCR测序，蛋白质组学和 重组抗体，将提供一个强大的平台，以进一步完善我们的理解如何体液 免疫力驱动人类的过敏性疾病。

Only a subset of patients with IgE-mediated food allergy develop clinical tolerance after oral immunotherapy (OIT), which has been attributed to the development of protective, functionally suppressive antibodies. However, those who lose tolerance are often seen to have an early transient increase in allergen- specific IgE. Previously, we have described the induction of allergen-specific memory B cells early in OIT, and these specific IgG B cells could serve as a reservoir of IgE memory via sequential class-switching. Therefore, the relative contribution of specific IgG B cells giving rise to protective IgG or IgA antibodies versus pathogenic IgE is critical to the development of immunological tolerance in OIT. Understanding the contributions of that B cell fate decision could lead to the development of new therapeutic modalities for allergic diseases. In OIT, we recently published that suppression of basophil sensitivity is a biomarker of tolerance. Functional suppression of basophils and not bulk levels of allergen-specific IgG is correlated with tolerance, suggesting that the antibody repertoire induced by OIT may be highly relevant to the development of tolerance. We have developed a highly specific fluorescent multimer to identify and characterize allergen-specific B cells in peanut OIT in order to define the clonal contributions of these B cells. Using these tools, we propose to track clonal evolution from the memory IgG B cells induced by OIT to the post-serum effector antibodies to explain how antibody evolution from specific IgG B cells influences clinical outcomes in OIT. Based on these findings, we hypothesize that allergen-specific memory IgG B cells can give rise to either protective or pathogenic antibodies that determine long-lived tolerance after OIT. Our approach combines the isolation of antigen-specific B cells for single-cell BCR sequencing, BCR repertoire analysis, and serum proteomics to dissect the clonality of serum antibodies to the peanut allergen, Ara h 2, over the course of OIT. We are uniquely positioned to conduct this study in that we have both serum and BCR repertoires from previously characterized OIT-treated patients. We will address our hypothesis in the following specific aims: (1) Evaluate the development of protective, functionally suppressive allergen-specific IgG in sustained tolerance after OIT; and (2) Evaluate the role of sequential switching in the loss of tolerance after OIT. We anticipate that the proposed studies will elucidate the connection between long-lasting clinical efficacy of OIT on a clonal level with protective and pathogenic antibodies, highlighting the critical role of memory allergen-specific IgG B cells and leading to new strategies for the treatment of food allergies. The development of techniques to track antigen-specific B cell fate, using BCR sequencing, proteomics and recombinant antibodies, will provide a powerful platform to further refine our understanding of how humoral immunity drives allergic disease in humans.