RECEPTOR-LIGAND INTERACTIONS IN CRYPTOCOCCOSIS

感染由于包囊真菌隐球菌新生是 受损患者发病率和死亡率的重要原因 宿主防御 吞噬细胞，尤其是巨噬细胞， 重要的作用，在包含这种无处不在的酵母在早期和 感染晚期。 然而，吞噬细胞 结合、吞噬并最终抑制或杀死C。新形动物是 不完全理解。 该计划将重点放在几个具体的 宿主吞噬细胞对C.新生儿：（1）调理素 吞噬细胞上介导C.新人类将会 其特征在于定量选择性调理的生物体的结合 与补体或免疫球蛋白在已知条件下禁用 特异性吞噬受体（例如，抗受体治疗 单克隆抗体、蛋白酶或二价阳离子螯合剂）。 此外，委员会认为， 通过选择的细胞因子调节受体-配体结合（例如，TNF， IFN-γ，GM-CSF）和细胞外基质蛋白（例如，纤连蛋白， 胶原蛋白）将被探索。 (2)生物化学的类型和顺序 将研究特异性受体-配体相互作用之后的事件。 要测量的早期事件包括特异性生物活性物质的产生。 磷脂产品（如磷酸肌醇、二酰基甘油、血小板 活化因子和花生四烯酸代谢物，包括洋地黄素 和白三烯）、激酶活化（蛋白激酶C易位）和 胞浆钙流 后来要研究的事件包括 呼吸爆发产物（如超氧阴离子和H2 O2），以及溶酶体 酶释放 对其中许多事件的反应不一致， 将使用以下方法测定单个吞噬细胞和吞噬细胞亚群 FACS和图像分析技术。 (3)触发这些生化反应 事件将与吞噬细胞容纳细胞的能力相关。 生物体通过安装功能反应，如吞噬作用，真菌抑制 和杀真菌活性。 隐球菌荚膜作为一种 毒力因子将通过比较包囊菌株来探索 缺乏荚膜的突变菌株。 这些研究的重点将是 对人巨噬细胞群（培养物衍生的和支气管肺泡的）， 然而，也将研究单核细胞和嗜中性粒细胞。

Infections due to the encapsulated fungus Cryptococcus neoformans are significant causes of morbidity and mortality in patients with impaired host defenses. Phagocytes, especially macrophages, presumably play important roles in containing this ubiquitous yeast in both the early and late stages of infection. However, the condition under which phagocytes bind, phagocytose, and eventually inhibit or kill C. neoformans are incompletely understood. This grant proposes to focus on several specific aspects of the host phagocyte response to C. neoformans: (1) Opsonic receptors on phagocytic cells that mediate binding of C. neoformans will be characterized by quantitating binding of organisms selectively opsonized with complement or immunoglobulins under conditions known to disable specific phagocytic receptors (e.g., treatment with anti-receptor monoclonal antibodies, proteases or divalent cation chelators). Moreover, the modulation of receptor-ligand binding by selected cytokines (e.g., TNF, IFN-gamma, GM-CSF) and extracellular matrix proteins (e.g., fibronectin, collagen) will be explored. (2) The type and sequence of biochemical events that follow specific receptor-ligand interactions will be studied. Early events to be measured include generation of specific bioactive phospholipid products (such as phosphoinositides, diacylglycerol, platelet activating factor, and arachidonate metabolites including prostaglandins and leukotrienes), kinase activation (protein kinase C translocation) and cytosolic calcium fluxes. Later events to be studied include generation of respiratory burst products (e.g. superoxide anion and H2O2), and lysosomal enzyme release. Heterogeneity of response to many of these events among individual phagocytes and phagocyte subpopulations will be determined using FACS and image analysis techniques. (3) Triggering of these biochemical events will be correlated with the ability of the phagocyte to contain the organism by mounting functional responses such as phagocytosis, fungistasis and fungicidal activity. The role cryptococcal capsule plays as a virulence factor will be explored by comparison of encapsulated strains with mutant strains that lack capsule. Emphasis in these studies will be on human macrophage populations (both culture-derived and bronchoalveolar), however, monocytes and neutrophils will also be studied.