RECEPTOR-LIGAND INTERACTIONS IN CRYPTOCOCCOSIS

由包裹的新生隐球菌引起的感染有 精神障碍患者发病和死亡的重要原因 主机防御。吞噬细胞，特别是巨噬细胞，可能在 在包含这种无处不在的酵母的早期和 感染的晚期。然而，吞噬细胞在何种条件下 结合、吞噬并最终抑制或杀死新生葡萄球菌 不完全理解。这笔赠款建议将重点放在几个具体的 宿主吞噬细胞对新生葡萄球菌的反应：(1)光学 吞噬细胞上介导新生杆菌结合的受体将是 以选择性调理的有机体的定量结合为特征的 在已知禁用条件下使用补体或免疫球蛋白 特异性吞噬细胞受体(例如，用抗受体治疗 单抗、蛋白水解酶或二价阳离子螯合剂)。此外， 由选定的细胞因子(例如，肿瘤坏死因子， 干扰素-γ、GM-CSF)和细胞外基质蛋白(例如，纤维连接蛋白， 胶原蛋白)将被探索。(2)生化反应的类型和顺序 将研究特定受体-配体相互作用之后的事件。 需要测量的早期事件包括产生特定的生物活性 磷脂产品(如磷脂酰肌醇、二酰甘油、血小板 激活因子和包括前列腺素在内的花生四烯酸代谢产物 和白三烯)、激酶激活(蛋白激酶C易位)和 胞内钙通量。以后要研究的事件包括产生 呼吸爆发产物(如超氧阴离子和过氧化氢)和溶酶体 酶的释放。对这些事件中许多事件的反应的异质性 单个吞噬细胞和吞噬细胞亚群将用 FACS和图像分析技术。(3)触发这些生化反应 这些事件将与吞噬细胞包含 通过提高功能反应，如吞噬、抑菌 和杀菌活性。隐球菌胶囊作为一种 毒力因子将通过对包膜菌株的比较来探索。 突变的菌株没有被膜。这些研究的重点将是 在人巨噬细胞群(包括培养来源和支气管肺泡)上， 然而，单核细胞和中性粒细胞也将被研究。

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.