MECHANISMS OF HUMAN BASOPHIL & MAST CELL DESENSITIZATION

嗜碱性粒细胞和肥大细胞介质的释放是两者的中心特征 急性和慢性过敏反应。然而，人们对此知之甚少 人类细胞中信号转导的生化性质 打字。这项建议的重点是研究，这些研究将阐明一些 IgE介导的激素和单价激素中的重要生化事件 诱导分泌。这些研究的主要目标是阐明 脱敏的机制虽然付出了巨大的努力，但也将 应用于理解激活事件。尤其是， 细胞内钙升高和蛋白激酶C在激活中的作用 并将进一步研究脱敏作用。我们已经证明了 IgE介导的人嗜碱性粒细胞和肺肥大细胞的组胺释放 伴随着细胞膜活性增加而来的是膜 蛋白激酶C和胞浆钙升高。详细研究 提示脱敏过程是介体特有的 被检查和调节脱颗粒的程度 (组胺释放)，嗜碱性粒细胞和肥大细胞调节激活 而不是细胞内钙的升高。 因此，该提案的一部分试图更详细地了解 蛋白激酶C活化与组胺释放的关系 PKC在调节介质释放中可能发挥的多重作用以及是否 PKC活性的瞬时激活是由于特定的 二酰甘油水平的调节。一系列探索性实验 被提出用来确定酪氨酸激酶活性是否在 在脱敏过程中。初步证据还表明，白三烯 与组胺释放不同，释放是由下调调控控制的 对钙的反应。拟议的研究将初步研究 钙离子反应下调与血管紧张素转换酶下调的关系 白三烯释放的调节。第二个主要研究领域将是 单细胞内观察到的钙振荡之间的关系 细胞和随后的介质释放。提出了几种方法来 测量单个细胞脱颗粒，以努力将这一结果关联起来 这与细胞内钙的早期振荡变化有关。在……里面 此外，钙振荡与白三烯的关系 将对释放进行检查。这项建议的第三个目的是研究 影响早期的脱敏事件之间的关系 中介物(组胺和白三烯)和细胞因子分泌 在分泌反应中发生的时间要晚得多。自细胞因子释放以来 似乎依赖于mRNA的积累，初步研究将集中在 信使核糖核酸积累的机制。

Basophil and mast cell mediator release is a central feature of both acute and chronic allergic reactions. However, little is known of the biochemical nature of signal transduction in the human cells of this type. This proposal focuses on studies which will elucidate some of the important biochemical events in both IgE mediated and univalent hormone induced secretion. The primary goals of these studies is to elucidate the mechanisms of desensitization although significant effort will also be applied towards understanding activation events. In particular, the role of cytosolic calcium elevations and protein kinase C in activation and desensitization will be further examined. We have demonstrated that IgE-mediated histamine release in both human basophils and lung mast cells is accompanied by the increased activity of membrane associated protein kinase C and elevations in cytosolic calcium. Detailed studies suggest that desensitization processes are specific for the mediator being examined and that for regulating the extent of degranulation (histamine release), the basophil and mast cell regulate the activation of protein kinase C rather than elevations in cytosolic calcium. Therefore, part of this proposal seeks to understand in greater detail the relationship between PKC activation and histamine release, the multiple roles PKC may play in regulating mediator release and whether the transient activation in PKC activity results from the specific regulation of diacylglycerol levels. A series of exploratory experiments are proposed to determine whether tyrosine kinase activity plays a role in desensitization. Preliminary evidence also suggests that leukotriene release, unlike histamine release, is controlled by the down-regulation of the calcium response. The proposed studies will initially examine the relationship between down-regulation of the calcium response and down- regulation of leukotriene release. A second primary area of study will be on the relationship between calcium oscillations observed in single cells and subsequent mediator release. Several methods are proposed to measure single cell degranulation in an effort to correlate this end point with the early oscillatory changes in cytosolic calcium. In addition, the relationship between calcium oscillations and leukotriene release will be examined. A third aim of this proposal is to study the relationship between desensitization events that affect the early mediators (histamine and leukotrienes) and cytokine secretion which occurs much later in the secretory response. Since cytokine release appears dependent on mRNA accumulation, initial studies will focus on the mechanisms of mRNA accumulation.