Human B1 Lymphopoiesis

描述（由申请人提供）：该项目涉及鉴定产生B1细胞（一种专门的B细胞亚群）的造血祖细胞。B1细胞负责产生所谓的“天然”抗体，这些抗体在适应性免疫开始之前保护免受微生物感染，并且似乎在免疫应答中起保护作用。 一些退化性疾病B1细胞与传统B细胞在许多其他重要方面不同，包括刺激T细胞、产生免疫抑制性IL-10和促炎性T细胞分化的偏斜。在小鼠中，B1细胞构成了一个独特的淋巴细胞谱系 它是由一种独特的淋巴细胞生成祖细胞产生的，与产生传统B2细胞的祖细胞分开。申请人实验室现已发现人B1细胞的表型同一性，如在别处更详细描述的。在掌握了人B1细胞的真实性质的情况下，本申请的目的是鉴定人B1细胞的特异性造血/淋巴细胞生成来源，并支持或反驳人B1细胞与其鼠对应物一样源自独特祖细胞的假设。鉴定和表征B1细胞祖细胞提供了能够操纵成熟B1细胞的发育并因此调节成熟B1细胞的数量和/或功能的希望，以通过特定的B1祖细胞定向疗法来增强或减少由B1细胞在健康和疾病中产生的特殊天然抗体和对T细胞的特殊作用。为了实现这一目标，将追求几个具体目标：1）建立淋巴细胞生成的模型系统，其通过过继转移至免疫受损动物来促进来自脐带血和/或骨髓造血干细胞的B1细胞的发育，并通过来自与间充质细胞共培养的造血干细胞的B1细胞发育的体外研究来补充; 2）通过从脐带血和骨髓中分选纯化和分化表型确定的群体，鉴定特异性产生B1细胞而不是B2细胞的最早祖细胞;并且，在本发明中，第三章通过特异性转录物的单细胞PCR评价内源性基因表达并与定义的淋巴细胞生成阶段，沿着评价表征祖细胞生成的成熟B1细胞的特征，并检查外源性细胞因子对B1细胞发育的影响。了解人类B1细胞的起源，最近才在正常和患者人群中发现，对于了解B1细胞发育和B1细胞生理学和病理生理学至关重要，这可能导致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。 公共卫生相关性：一群专门的B淋巴细胞，称为B1细胞，产生所谓的“天然”抗体，保护免受微生物感染，但与自身免疫有关。尽管在动物中得到了很好的描述，但B1细胞只是最近才由申请人实验室在人体中鉴定出来，该实验室确定了这些免疫细胞的表型或地址。我们现在提出鉴定人B1细胞祖细胞，其是B1细胞的干细胞并产生这种特化群体;人B1细胞祖细胞的鉴定和表征将使设计B1细胞定向疗法以增加保护性天然抗体或减少自身免疫反应成为可能。

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.