NEUTROPHIL ACTIVATION BY VIRUSES AND MAMMALIAN LECTINS

在呼吸道病毒中，甲型流感病毒（IAV）特别容易感染 引起细菌双重感染。 这些感染是导致 发病率和死亡率。 有令人信服 有证据表明，获得性IAV诱导的吞噬细胞功能缺陷是一种免疫缺陷。 细菌二重感染的重要原因。 IAV的约束力 血凝素与中性粒细胞上携带唾液酸的受体位点结合 介导细胞功能的抑制。 初步研究表明， 唾液酸白蛋白、CD 45、唾液酸-Le/x和神经节苷脂是其中的位点。 绑定 我们建议确认IAV与这些位点结合， 结合的特定唾液酸-Le/x承载蛋白，决定了 各种结合蛋白被IAV干扰（即内化、加帽）， 并确定哪些地点在数量上最重要， 功能上。 我们的初步数据与假设相符 单个糖蛋白受体介导失活。 The definitive 对这一理论的检验将涉及消除特定的 中性粒细胞糖蛋白在HL 60细胞中的表达 RNA或基因靶向）技术。 鉴定IAV的功能重要的糖蛋白受体是 不太可能提供停用的完整解释。 我们还将 需要确定IAV颗粒如何干扰这些受体， 失活发生。 IAV颗粒与肺的预孵育 表面活性蛋白D（SP-D）降低IAV引起中性粒细胞 功能障碍，同时显着增强IAV刺激免疫系统的能力， 呼吸爆发反应 然而，与SP-D复合的IAV结合至 中性粒细胞通过与未调理的IAV相同的机制（即通过附着 至带有硅酸的中性粒细胞膜组分）。 使用 重组，野生型和突变体，SP-D制剂，我们将确定 IAV颗粒与SP-D的“调理作用”改变的机制 IAV与中性粒细胞相互作用的功能结果。 我们将 表征IAV与SP-D孵育后形成的聚集体（通过 光散射，荧光和EM技术），并确定如何这些 聚集体与嗜中性粒细胞结合[通过鉴定特异性结合位点， 证明了这些结合位点如何被扰动（例如加帽， 在完整细胞中内化）。 我们的假设是SP-D 保护作用不是由于改变了哪些中性粒细胞受体 而是来自SP-D改变IAV性质的能力 粒子

Among respiratory viruses influenza A virus (IAV) is particularly prone to cause bacterial superinfections. These infections are the major cause of morbidity and mortality during IAV epidemics. There is compelling evidence that an acquired IAV-induced defect in phagocyte function is an important cause of bacterial superinfection. Binding of the IAV hemagglutinin to sialic acid-bearing receptor sites on the neutrophil mediates depression of cell function. Preliminary studies indicate that leukosialin, CD45, sialyl-Le/x, and gangliosides are among the sites bound. We propose to confirm that IAV binds to these sites, establish specific sialyl-Le/x bearing proteins which are bound, determine how the various binding proteins are perturbed (i.e. internalized, capped) by IAV, and establish which sites are most important quantitatively and functionally. Our preliminary data are compatible with the hypothesis that a single glycoprotein receptor mediates deactivation. The definitive test of this theory will involve eliminating expression of specific neutrophil glycoproteins in HL60 cells using recombinant (i.e. antisense RNA or gene targeting) techniques. Identification of functionally important glycoprotein receptors for IAV is unlikely to provide a full explanation for deactivation. We will also need to establish how IAV particles perturb these receptors such that deactivation occurs. Pre-incubation of IAV particles with pulmonary surfactant protein D (SP-D) reduces the ability of IAV to cause neutrophil dysfunction, while markedly enhancing the ability of IAV to stimulate a respiratory burst response. However, IAV complexed with SP-D binds to neutrophils via the same mechanism as unopsonized IAV (i.e. via attachment to sialic-acid bearing neutrophil membrane components). Using recombinant, wild type and mutant, SP-D preparations we will determine the mechanisms through which "opsonization" of IAV particles with SP-D alters the functional outcome of IAVs interaction with neutrophils. We will characterize the aggregates formed after incubation of IAV with SP-D (by light scattering, fluorescent and EM techniques) and determine how these aggregates bind to neutrophils [by identifying specific binding sites and demonstrating how these binding sites are perturbed (e.g. capped, internalized) in intact cells]. Our working hypothesis is that SP-D's protective effect results not from changing which neutrophil receptors bind IAV but rather from SP-D's ability to change the nature of the IAV particle.