DIFFERENTIATION OF MAST CELL PROGENITORS

肥大细胞的体外分化伴随着大规模的 祖细胞免疫球蛋白E受体阳性时的表型变化， 颗粒状肥大细胞。许多表型变化都是由 肥大细胞和嗜碱性粒细胞特有的基因产物的表达。 尽管这些特点为研究提供了一个有吸引力的模型系统 在细胞分化方面，缺乏明确的肥大祖细胞 细胞(大多数研究人员使用未分离的骨髓)和使用 IL-3产生长期肥大细胞培养不允许 狭隘聚焦窗口的表型变化。我们已经定义了一个 肥大细胞前体细胞分化的晚期、专一阶段 就在肉芽形成之前。这个受控于肥大细胞的祖细胞不 需要具有差异性的IL-3，但确实需要由 来自结缔组织的成纤维细胞，如胚胎皮肤。这款车 系统为分析肥大细胞生成这一过程提供了独特的优势 在即刻过敏性疾病的发展过程中起重要作用。 首先，将使用体外分化系统来跟踪 晚期祖细胞对Defined反应的离散变化 各种因素。分离的肥大细胞定向祖细胞的制备将 用纯化的成纤维细胞衍生因子进行表型鉴定和触发。 细胞激活将通过以下方式进行监测： 细胞内钙和氚胸苷的掺入。变化 在高亲和力IgE受体，生长因子受体， 组胺的生物合成和颗粒组装将按顺序相关 通过信号转导。 第二，分化系统将用于#年的大鼠研究 用于检测糜酶、RMCP-II、羧肽酶A或肝素 胚胎皮肤培养的肥大细胞中的蛋白多糖 单层。这将使我们能够研究肥大细胞的异质性。 (粘膜与结缔组织类型)在体外系统中。 第三，导致原始骨过渡的因素。 肥大细胞的骨髓祖细胞向IL-3非依赖性方向发展 承诺的祖先将通过旨在模仿的实验来确定 在体外，两种最有可能在体内产生 坚定的祖细胞：从肠道中完全脱颗粒的肥大细胞 粘膜引流到MLN，或骨髓前体细胞运输到 作为原始祖先的MLN正在发展为承诺 祖细胞在原地。

Mast cell differentiation in vitro is accompanied by large-scale phenotypic changes as progenitors become IgE receptor-positive, granulated mast cells. Many of the phenotypic changes occur by expression of gene products unique to mast cells and basophils. Although these features make for an attractive model system for studies of cellular differentiation, the lack of a defined progenitor for mast cells (most investigators use unfractionated bone marrow) and the use of IL-3 to generate long term mast cell cultures has not allowed for a narrowly-focused window on the phenotypic changes. We have defined a late, committed stage in the differentiation of the mast cell progenitor just prior to granulation. This mast cell-committed progenitor does not require IL-3 of differentiation but does require factors provided by fibroblasts from connective tissue such as embryonic skin. This model system provides unique advantages to analyze mastocytogenesis, a process important in the development of diseases of immediate hypersensitivity. First, the in vitro differentiation system will be used to follow discrete changes in late-stage progenitor cells responding to defined factors. Preparations of isolated mast cell-committed progenitors will be phenotyped and triggered with purified fibroblast-derived factor. Cell activation will be monitored by following the mobilization of intracellular calcium and incorporation of tritiated thymidine. Changes in expression of high affinity IgE receptors, growth factor receptors, histamine biosynthesis, and granule assembly will correlate in sequence with signal transduction. Second, the differentiation system will be adapted for rat studies in order to detect chymase, RMCP-II, carboxypeptidase A, or heparin proteoglycan in mast cells derived from culture on embryonic skin monolayers. This will allow us to study mast cell heterogeneity (mucosal vs connective tissue type) in an in vitro system. Third, the factors which cause the transition of the primitive bone marrow progenitor for mast cells to progress to the IL-3 independent committed progenitor will be determined by experiments designed to mimic in vitro the two most likely in vivo milieus that give rise to the committed progenitor: completely degranulated mast cells from the gut mucosa draining into the MLN, or bone marrow progenitors trafficking to the MLN as a primitive progenitor and progressing into committed progenitors in situ.