Human B1 Lymphopoiesis

描述(由申请人提供)：这个项目涉及到产生B1细胞的造血祖细胞的鉴定，B1细胞是B细胞的一个特殊亚群。B1细胞负责产生所谓的“天然”抗体，这种抗体在适应性免疫开始之前就能防止微生物感染，并似乎在 一些退化性疾病。B1细胞在许多其他重要方面不同于传统的B细胞，包括刺激T细胞，产生免疫抑制IL-10，以及偏向促炎T细胞分化。在小鼠中，B1细胞构成了一个独特的淋巴细胞系 这是由一种独特的淋巴祖细胞产生的，它独立于产生传统B2细胞的祖细胞。申请实验室现在已经发现了人类B1细胞的表型特征，这一点在其他地方有更详细的描述。鉴于人类B1细胞的真实性质，这项应用的目的是确定人类B1细胞的特定造血/淋巴来源，并支持或驳斥人类B1细胞与其小鼠的同类细胞一样，来自独特的祖细胞的假说。鉴定和鉴定B1细胞前体有望控制成熟B1细胞的发育，从而调节成熟B1细胞的数量和/或功能，以增强或减少特殊的天然抗体，以及通过特定的B1祖细胞定向治疗在健康和疾病中对B1细胞产生的T细胞的特殊影响。为了实现这一目标，我们将致力于以下几个具体目标：1)建立一个通过过继移植到免疫受损动物体内，促进脐血和/或骨髓造血干细胞的B1细胞发育的淋巴生成模型系统，并辅之以从与间充质细胞共培养的造血干细胞体外发育B1细胞的研究；2)通过对脐血和骨髓表型定义的群体的分类、纯化和分化，确定特异性地产生B1细胞而不是B2细胞的最早的祖细胞；3)通过对特定转录物的单细胞聚合酶链式反应评估内源性基因表达，并与已定义的淋巴系发育阶段进行比较，以及评估祖细胞生成的成熟B1细胞的特征，以及检查外源细胞因子对B1细胞发育的影响，来表征已鉴定的产生人类B1细胞的祖细胞。了解人类B1细胞的起源，对于了解B1细胞的发育和B1细胞的生理学和病理生理学是至关重要的，这可以导致对B1细胞数量和功能的治疗操作的新策略，以防止感染和其他疾病。 与公共卫生相关：一种特殊的B淋巴细胞群，称为B1细胞，它能产生所谓的“天然”抗体，这种抗体可以预防微生物感染，但与自身免疫有关。尽管B1细胞在动物中得到了很好的描述，但申请实验室最近才在人类中发现了B1细胞，该实验室确定了这些免疫细胞的表型或地址。我们现在建议鉴定人类B1细胞前体细胞，它是B1细胞的干细胞，并产生这种特殊的群体；鉴定和鉴定人类B1细胞前体细胞将使设计B1细胞定向治疗成为可能，以增加保护性天然抗体或减少自身免疫反应。

DESCRIPTION (provided by applicant): This project concerns identification of the hematopoietic progenitor cell that gives rise to B1 cells, a specialized subpopulation of B cells. B1 cells are responsible for producing so-called "natural" antibodies that protect against microbial infection prior to the onset of adaptive immunity and appear to play a protective role in some degenerative diseases. B1 cells differ from conventional B cells in many other important ways, including stimulation of T cells, production of immunosuppressive IL-10, and skewing of pro-inflammatory T cell differentiation. In mice, B1 cells constitute a distinct lymphocyte lineage that is generated by a unique lymphopoietic progenitor, separate and apart from the progenitor that gives rise to conventional B2 cells. The applicant laboratory has now discovered the phenotypic identity of human B1 cells, as described in more detail elsewhere. With the true nature of human B1 cells in hand, the objective of this application is to identify the specific hematopoietic/lymphopoietic origin of human B1 cells, and to support or refute the hypothesis that human B1 cells, like their murine counterparts, derive from a unique progenitor. Identifying and characterizing the B1 cell progenitor holds out the promise of being able to manipulate the development, and hence modulate the number and/or function, of mature B1 cells, to enhance or diminish the special natural antibodies, and the special effects on T cells, produced by B1 cells, in health and disease, through specific B1 progenitor cell-directed therapies. To achieve this goal, several specific aims will be pursued to: 1) Establish a model system for lymphopoiesis that fosters the development of B1 cells from cord blood and/or bone marrow hematopoietic stem cells through adoptive transfer to immunocompromised animals, supplemented by in vitro studies of B1 cell development from hematopoietic stem cells co-cultured with mesenchymal cells; 2) Identify the earliest progenitor that specifically produces B1 cells and not B2 cells through sort-purification and differentiation of phenotypically defined populations from cord blood and bone marrow; and, 3) Characterize the identified progenitor that produces human B1 cells by evaluating endogenous gene expression through single cell PCR of specific transcripts and comparison with profiles of defined lymphopoietic stages, along with evaluation of the features that characterize progenitor-generated mature B1 cells, and examination of exogenous cytokine influences on B1 cell development. Understanding the origin of human B1 cells, which have only recently been identified in normal and patient populations, is critical to understanding B1 cell development and B1 cell physiology and pathophysiology, which can lead to novel strategies for therapeutic manipulation of B1 cell numbers and function to protect against infectious and other diseases. PUBLIC HEALTH RELEVANCE: A specialized population of B lymphocytes, termed B1 cells, produces so-called "natural" antibodies that protect against microbial infection but are associated with autoimmunity. Although well described in animals, B1 cells were only recently identified in humans by the applicant laboratory which determined the phenotype, or address, of these immune cells. We now propose to identify the human B1 cell progenitor which is the stem cell for B1 cells and gives rise to this specialized population; identification and characterizatio of the human B1 cell progenitor will make it possible to design B1 cell-directed therapies to increase protective natural antibodies or decrease autoimmune reactions.