The Role of CD32 in the Basophil Response to Specific Immunotherapy

描述(申请人提供)：特异性免疫疗法(SIT)是治疗过敏性疾病的主要方法。虽然有几个强有力的假设为这种治疗方法的成功(或缺乏)提供了解释，但这些假设中的大多数都没有在人类身上进行完全的检验。长期以来的观察之一是，SIT诱导产生特异性的免疫球蛋白抗体，但这些抗体对SIT疗效的作用机制尚不清楚。这项建议将检验这一假设，即阻断免疫球蛋白通过细胞表面CD32b(FcgRIIb)影响人嗜碱细胞反应。现有有限的文献验证这一假说是相互矛盾的，但有新的信息可能有助于探索这一问题，并解释在SIT临床研究中可能发生的潜在生物变异。本实验室的初步研究表明，CD32a和CD32b的相对比例可以随着细胞因子的暴露而改变。现有文献对可能介导CD32效应的信号转导机制也是模棱两可的。因此，这项建议的第一个目的是扩大我们对CD32表达调控及其信号机制的了解。这些知识将被用来进一步改进SIT临床研究的设计和解释，该研究在 该提案的第二个目的。临床研究的目的是为患者提供探索所提出的假说所需要的，但我们将把体外嗜碱性细胞功能测试的结果与实验性鼻变应原挑战所衡量的SIT的临床结果结合起来。第三个目标列出了在临床试验期间将进行的体外测试，它将集中在嗜碱性粒细胞和CD32生物学的几个领域；列举阻断IgG亚型的数量和亲和力，用测量封闭抗体效果的传统方法锚定研究，引入一种新的方法来评估CD32对嗜碱性细胞反应的贡献，测试嗜碱性细胞的表型变化，特别是当它与CD32信号通路的组成部分相关时，并计数患者的CD32基因型别，因为现在很明显，多态改变了CD32与IgG的结合。有了这一新的信息，我们有望证明CD32参与了抗体阻断效应，或理解了为什么它不参与。

DESCRIPTION (provided by applicant): Specific immunotherapy (SIT) is a mainstay approach in the treatment of allergic diseases. While there are several strong hypotheses that provide an explanation for the success (or lack thereof) of this therapeutic approach, most of these hypotheses are incompletely examined in humans. One of the longstanding observations is that SIT induces enhanced production of specific IgG antibodies but the mechanism by which these antibodies may contribute to the efficacy of SIT is not well understood. This proposal will test th hypothesis that blocking IgG exerts an influence on the human basophil response through cell surface CD32b (FcgRIIb). The limited existing literature testing this hypothesis is contradictory but there is new information that may help to explore this question and account for potential biological variation that may occur in a clinical study of SIT. Preliminary studies in this laboratry demonstrate that the relative proportion of CD32a and CD32b can be altered with cytokine exposure. Existing literature is also ambiguous on the signal transduction mechanisms that may mediate CD32 effects. Therefore, the first aim of this proposal is to expand our knowledge of the regulation of CD32 expression and its signaling mechanisms. This knowledge will be used to further improve on the design and interpretation of a clinical study of SIT that is proposed in the second aim of the proposal. The purpose of the clinical study is to provide the patients needed to explore the proposed hypothesis but we will couple the results from the in vitro testing of basophil function to the clinical outcomes of SIT as measured by experimental nasal allergen challenges. The third aim sets out the in vitro testing that will be done during the clinical trial It will focus on several areas of basophil and CD32 biology; to enumerate the quantity and affinity of blocking IgG isotypes, to anchor the study with a traditional method of measuring blocking antibody effect, to introduce a new method to assess the contribution CD32 to the basophil response, to test the basophil for changes in its phenotype, especially as it relates to components of the CD32 signaling pathways and to enumerate the patients' CD32 genotype since it is now apparent that polymorphisms alter CD32 binding to IgG. It is expected that with this new information in hand, we will be able to demonstrate that CD32 participates in blocking antibody effect or understand why it does not.