C3A ACTIVATION OF LEUKOCYTES IN INFLAMMATION

描述（改编自研究者摘要）： 白细胞是急性和慢性炎症的特征， 疾病 大量证据表明，中性粒细胞、单核细胞和 嗜酸性粒细胞通过特异性趋化性被吸引到炎症部位， 因子，包括补体因子如C3 a和C5 a，其中 然后，募集的细胞可以进一步被细胞和/或体液免疫激活。 介质在局部组织部位。 C3 a是由第三个也是最多的 补体的丰富成分，并已显示出选择性诱导 嗜酸性粒细胞的趋化性和脱颗粒，但中性粒细胞没有。 我们 已发表的数据表明，中性粒细胞的C3 a活化完全是 继发于嗜酸性粒细胞的C3 a刺激（Daffern等，J. Exp. Med. 181：2129，1995）。 C3 a和C5 a的受体表达于细胞表面， 许多炎症细胞，这些细胞通过细胞内 这些机制尚未被完全描述或理解。 我们 初步的功能研究表明，C3 a诱导更多的独特或 在嗜酸性粒细胞，也许还有单核细胞中， 尽管在中性粒细胞上存在C3 a受体， 细胞类型。 叶博士的实验室最近分离出了编码 C3 a受体（C3 aR）是七螺旋跨膜受体的新成员， 已知为视紫红质家族的一类受体（Roglic等，BBA， 1305：39，1996）。 人C3 aR的cDNA编码一个G 具有独特细胞外环的蛋白偶联受体（~ 170个氨基酸） 在第四和第五跨膜区之间。 这个大 细胞外环结构是一个特征，没有观察到其他成员的 迄今已阐明的视紫红质受体家族。 我们建议， 异常大的细胞外环是一个主要的候选者， 完整C3 a分子的受体结合/效应位点。 我们有 产生针对C3 aR的大细胞外环的多克隆抗体， 该免疫试剂检测天然细胞表面受体。 生物活性 合成的C3 a肽类似物，这是我们多年前设计的， 实验室，现在也有望成为绘制效应器的有价值的工具 C3 a受体上的结合位点。 我们的研究将探索C3 a 嗜中性粒细胞、单核细胞和嗜酸性粒细胞中的信号传导/转导机制， 以及确定C3 a/C3 aR相互作用的特征， C3 a受体分子上效应位点的定位。 在这 应用程序，我们提出了一个合作研究，比较功能 反应，结合参数和中性粒细胞， 单核细胞和嗜酸性粒细胞被C3 a差异激活 过敏毒素

DESCRIPTION (Adapted from Investigator's abstract): Infiltration of leukocytes is a characteristic of both acute and chronic inflammatory diseases. Extensive evidence indicates that neutrophils, monocytes and eosinophils are attracted to sites of inflammation by specific chemotactic factors, including complement factors such as C3a and C5a, where the recruited cells may then be further activated by cellular and/or humoral mediators at local tissue sites. C3a is generated from the third and most abundant component of complement and has been shown to selectively induce chemotaxis and degranulation of eosinophils, but not neutrophils. Our published data indicates that C3a activation of neutrophils is entirely secondary to C3a stimulation of eosinophils (Daffern et al., J. Exp. Med. 181:2129, 1995). Receptors to C3a and C5a are expressed on the surface of many inflammatory cells and these cells are activated through intracellular mechanisms that have yet to be fully characterized or understood. Our preliminary functional studies suggest that C3a induces more unique or different signaling events in eosinophils, and perhaps monocytes, than it does in neutrophils despite the presence of C3a receptors on each of these cell types. Dr. Ye's laboratory has recently isolated the cDNA coding for the C3a receptor (C3aR), a new member of the heptahelical transmembrane class of receptors known as the Rhodopsin family (Roglic et al. BBA, 1305:39, 1996). The cDNA for human C3aR has been shown to encode a G protein-coupled receptor with a unique extracellular loop (-170 amino acids) between the fourth and fifth transmembrane regions. This large extracellular loop structure is a feature observed in no other member of the Rhodopsin family of receptors elucidated to date. We propose that this unusually large extracellular loop is a prime candidate for being the receptor binding/effector site of the intact C3a molecule. We have generated polyclonal antibodies to the large extracellular loop of C3aR and this immunoreagent detects the native cell surface receptor. The bioactive synthetic C3a peptide analogues, that were designed years earlier in our laboratory, now also promise to be valuable tools in mapping the effector binding site on the C3a receptor. Our studies will explore C3a signaling/transduction mechanisms in neutrophils, monocytes and eosinophils, as well as determine characteristics of the C3a/C3aR interactions and mapping of the effector site on the C3a receptor molecule. In this application, we propose a collaborative study to compare the functional responses, binding parameters and molecular mechanisms by which neutrophils, monocytes and eosinophils are differentially activated by the C3a anaphylatoxin.