SIGA/SIGA/SIGAR MUCOSAL DEFENSE SYS

描述 (改编自申请人的摘要)在粘膜分泌物中发现IgA 有两种不同的形式，单体IgA(MIGA)和二聚体分泌型IgA (SIGA)。这两种形式的IgA传统上都被认为是一种被动的 在粘膜防御中的作用，阻止粘连和中和毒素。这个 粘膜上MIGA Fc部分(FcamR)受体的存在 吞噬细胞暗示着更活跃的作用。人们一直认为SIGA分享了 Fc受体与MIGA相同，但尚未被直接证实。 在SIGA的结构中存在附加链(J链和秘书 组件)可能会阻止将其FC域绑定到传统FC 感受器。这向我们表明，SIGA可能会利用不同的 吞噬细胞受体。申请者的部分特征是6okD PMN细胞表面的蛋白质，与SIgA结合，但不与其他 免疫球蛋白亚型。申请人提出这种蛋白质是一种 SIgA的唯一受体，已将其命名为SIGAR。申请人 假设不同形式的IgA-在 通过这两种途径调节的粘膜吞噬防御 不同的受体，FCA-R和SIGAR。申请者将调查 通过四个具体目标进行假设。1)。他将塑造和克隆 SIGAR。最初，他将确定SIGAR是否与GPI相关， 糖基化的或与其他表面蛋白结合的。这会有帮助的 他在确定CDNA的大致大小时。然后将会有一个探测器 由部分蛋白质序列构建而成，将用于筛选 HL-60CDNA文库。CDNA将被克隆和测序。2)。这个 中性粒细胞、单核细胞、巨噬细胞和嗜酸性粒细胞表面SIGAR的表达 要下定决心。他还将确定这些基因的表达是如何调节的 当血细胞移动到粘膜时。3)。他将描述 SIgA与SIGAR结合的亲和力和阳离子要求 确定蛋白质的哪些片段介导结合以及受体如何 信号。4)。他将确定SIgA与PMN的相互作用， 吞噬中的单核细胞、巨噬细胞和嗜酸性粒细胞，超氧化物 世代和杀戮分析。这些研究的完成应该会表明 预防和/或干预感染-炎症过程的更好方法 在肺和其他粘膜部位。

DESCRIPTION (Adapted from the applicant's abstract) IgA is found in mucosal secretions in two different forms, monomeric IgA (mIgA) and dimeric secretory IgA (sIgA). Both forms of IgA have traditionally been felt to play a passive role in mucosal defense, blocking adherence and neutralizing toxins. The presence of a receptor for the Fc portion of mIgA (FcamR) on mucosal phagocytes suggest a more active role. It has been assumed that sIgA shared the same Fc receptor as mIgA but this has not been directly demonstrated. The presence of additional chains in sIgA's structure (J chain and secretary component) possibly prevent binding of its Fc domains to traditional Fc receptors. This suggested to us that sIgA may utilize a different phagocytic receptor. The applicant has partially characterized a 6OkD protein from the cell surface of PMN which binds sIgA but not other immunoglobulin isotypes. The applicant proposes that this protein is a unique receptor for sIgA and has termed it sIgAR. The applicant hypothesized that different forms of IgA -have important effects in phagocytic defense of the mucosa which are mediated through these two different receptors, Fca-R and sIgAR. The applicant will investigate the hypotheses through four specific aims. 1). He will characterized and clone the sIgAR. Initially, he will determine if the sIgAR is GPI-linked, glycosylated or associated with other surface proteins. This will assist him in determining the approximate size of the CDNA. A probe will then be constructed from a partial protein sequence which will be used to screen an HL-60 CDNA library. The CDNA will be cloned and sequenced. 2). The expression of the sIgAR on PMN, monocytes, macrophages and eosinophils will be determined. He will also determine how expression is modulated on these blood cells as they move to the mucosa. 3). He will characterize the affinity and cation requirements of the binding of sIgA to sIgAR, and will determine which segments of the protein mediate binding and how the receptor signals. 4). He will determine the interaction of sIgA with PMN, monocytes, macrophages and eosinophils in phagocytosis, superoxide generation and killing assays. Completion of these studies should suggest better ways to prevent and/or intervene in infectious-inflammatory processes in the lung and at other mucosal sites.