Desensitization of Human Mast Cells and Basophils: Mechanisms and Potential Utili

哮喘和过敏性疾病是重要的健康问题，肥大细胞和可能的嗜碱性粒细胞是哮喘和过敏性疾病的主要原因。 IgE介导的人类立即过敏的主要效应细胞。调查人员以前的工作 参与项目1包括开发类胰蛋白酶作为肥大细胞活化的临床标志物;发现 哮喘气道和全身过敏反应期间肥大细胞的活化;识别两种类型的 人肥大细胞（MCT和MCTc），基于其分泌颗粒和表面的蛋白酶含量 CD 88的表达;发现Fc γ RII的活化形式，CD 32a，在CD 88上组成性表达， 皮肤MCTC细胞表面的Syk缺陷;以及在具有非荧光素酶表型的嗜碱性粒细胞中和具有非荧光素酶表型的嗜碱性粒细胞中发现Syk缺陷。 抗原脱敏后肥大细胞的体外培养。本项目的三个具体目标是： 1.验证人肥大细胞和嗜碱性粒细胞在体外经历交叉脱敏的假设。 不同抗原和通过Fc ε RI和Fc γ RIIa的异源脱敏。事实上，初步 数据表明，当MCTc型肥大细胞被IgE抗DNP致敏然后脱敏时， 在低剂量的DNP-BSA下，发生交叉脱敏和异源脱敏。 2.探讨Src和/或Syk对人肥大细胞脱敏的体外机制 酪氨酸激酶虽然Syk耗尽似乎是可能的，但林恩和/或Fyn的参与是不确定的。 此外，信号转导的亚细胞区室化对于脱敏和 激活将被检查。与项目3合作研究林恩激酶参与 脱敏，以及项目4关于鞘氨醇激酶-1参与脱敏的研究。 人肥大细胞和嗜碱性粒细胞促进了这些机制研究。 3.确定人体受试者体内青霉素脱敏是否产生抗原交叉脱敏 并从外周血嗜碱性粒细胞中消耗Syk。这 临床研究将开始将我们的体外发现转化为体内情况。 由于脱敏引起的临床耐受性可以通过其快速的免疫耐受性来与由于免疫治疗引起的临床耐受性区分。 诱导（小时）和过敏原给药停止后的短持续时间（天）。我们假设 脱敏主要靶向肥大细胞和嗜碱性粒细胞。更准确地了解其特征 和脱敏背后的机制将使医生能够更好地利用这种方法， 减少肥大细胞/嗜碱性粒细胞介导的对哮喘和过敏性疾病的贡献。

Asthma and allergic diseases are important health concerns, and mast cells and possibly basophils are the major effector cells of IgE-mediated immediate hypersensitivy in humans. Previous work by the investigators involved in Project 1 includes developing tryptase as a clinical marker for mast cell activation; finding activation of mast cells in the asthmatic airway and during systemic anaphylaxis; identifying two types of human mast cells (MCT and MCTc) based on the protease content of their secretory granules and the surface expression of CD88; discovering the activating form of FcyRII, CD32a, constitutively expressed on the surface of skin MCTC cells; and finding Syk-deficiency in basophils with the non-releaser phenotype and in mast cells after antigen desensitization in vitro. The three specific aims of the current project are to: 1. Test the hypothesis that human mast cells and basophils in vitro undergo cross-desensitization to different antigens and heterologous desensitization through FcsRI and FcvRlla. Indeed, preliminary data suggest that when mast cells of the MCTc type are IgE anti-DNP-sensitized and then desensitized with low doses of DNP-BSA, both cross-desensitization and heterologous desensitization occurs. 2. Explore in vitro the mechanism(s) for desensitization of human mast cells involving Src and/or Syk tyrosine kinases. Although Syk depletion seems likely, the involvement of Lyn and/or Fyn is uncertain. Further, the possibility that subcellular compartmentalization of signaling differs for desensitization and activation will be examined. Collaborations with Project 3 on studies of Lyn kinase involvement in desensitization, and with Project 4 on the involvement of sphingosine kinase-1 in desensitization of human mast cells and basophils facilitate these mechanistic studies. 3. Determine whether penicillin desensitization of human subjects in vivo produces antigen crossdesensitization of mast cells and basophils and depletes Syk from peripheral blood basophils. This clinical study will begin to translate our in vitro findings to the in vivo situation. Clinical tolerance due to desensitization can be distinguished from that due to immunotherapy by its rapid induction (hours) and short persistence (days) once allergen administration ceases. We hypothesize that desensitization targets primarily mast cells and basophils. Understanding more precisely the characteristics of and the mechanism(s) behind desensitization will enable physicians to better utilize this approach to reduce mast cell/basophil-mediated contributions to asthma and allergic diseases.