MAST CELL DIFFERENTIATION IN VITRO

肥大细胞是研究细胞免疫功能的重要模型 分化，因为从祖细胞的表型变化 细胞与肥大细胞之间的相互作用是巨大的， 与其他细胞相比，分化似乎很少 如B淋巴细胞。 我们已经定义了一个晚期的， 在肥大细胞祖细胞分化之前， 颗粒化 这种肥大细胞定向祖细胞不 需要IL-3用于分化，但确实需要因子或 由结缔组织微环境提供的因子， 鼠胚胎皮肤 如果肥大细胞定向祖细胞 可以成功地分离出结缔组织因子 鉴定，一个明确的体外分化系统可以 发展到个别检查离散的变化， 肥大细胞表型。 首先，我们提出了一种新的体外分化系统， 由此可以通过以下方法研究几种肥大细胞特征中的任何一种： 在晚期祖细胞对特定的 因素 为实现这一目标，将采取以下战略 使用：我们将获得肥大细胞的纯化制剂- 基于胚胎皮肤亲和力的定向祖细胞 单层。 这些祖细胞的表型将是 测定 我们将准确地确定因素或因素， 小鼠胚胎皮肤的单层， 肥大细胞定向祖细胞向肥大细胞的分化 细胞 当这完成时，分离的祖细胞将被分离。 用所需因子的纯化制剂触发， 检查激活事件的变化，高亲和力 IgE受体和生长因子受体，以及 去分化 其次，我们建议使用肥大细胞定向祖细胞， 文化系统中描述的赠款提案，以确定是否 已知的IgE调节因子也影响肥大细胞 细胞分化 第三，我们建议将这种分化系统用于大鼠， 为了检测糜酶、羧肽酶A或 体外培养肥大细胞中肝素蛋白多糖 胚胎皮肤单层。 这将使我们能够研究肥大细胞 异质性（体外试验中的粘膜型与结缔组织型） 系统

The mast cell is an attractive model system for studies of cellular differentiation because the phenotypic changes from progenitor cell to mast cell are great and the signals required to induce differentiation appear to be few as compared with other cells such as B lymphocytes. 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 for differentiation but does require a factor or factors provided by a connective tissue microenvironment such as murine embryonic skin. If the mast cell-committed progenitor can be successfully isolated and the connective tissue factors identified, a well-defined in vitro differentiation system could be developed to individually examine discrete changes that account for the mast cell phenotype. First, we propose to develop a new in vitro differentiation system whereby any of several mast cell features can be studied by following the response of late-stage progenitor cells to defined factors. For the goal to be realized, the following strategy will be used: We will obtain a purified preparation of mast cell- committed progenitors based on affinity for embryonic skin monolayers. The phenotype of these progenitors will be determined. We will precisely identify the factor or factors in monolayers of murine embryonic skin which are required for differentiation of the mast cell committed progenitor into mast cells. When this is done, the isolated progenitor cells will be triggered with purified preparations of the required factor to examine changes in activation events, expression of high-affinity IgE receptors and growth factor receptors, and the ability to dedifferentiate. Second, we propose to use the mast cell-committed progenitor culture system described in the grant proposal to determine if there are any known IgE regulatory factors which also affect mast cell differentiation. Third, we propose to adapt this differentiation system for rat studies in order to detect chymase, 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.