Physiological and cell biological studies on dendritic cells

树突状细胞（dc）的抗原摄取、加工和递呈已经成为细胞生物学方法的一部分。关键事件发生在对炎症刺激的反应正在发育和成熟的dc中。本项目的目的是确定免疫刺激树突状细胞的发育阶段并阐明抗原加工的调节机制。得到如下结果：1) DCs在吞噬细胞形成mhc肽复合物方面效率异常高，比暴露于预处理肽的效率高1-1万倍。在体内，当短命的迁移性dc通过传入淋巴管迁移到淋巴结的T细胞区时，也观察到类似的现象。2)吞噬注射微球后，约25%的炎症单核细胞迁移到引流淋巴结T区，表达树突状细胞限制性标记物和高水平的共刺激分子。3)利用信号序列陷阱法从小鼠骨髓来源的DC cDNA文库中分离出更多的MDC。这两种趋化因子均由体外分化自骨髓前体细胞的DC和来自组织的成熟DC表达，并由T区DC组成，以吸引T细胞。4)基于CD11c和CD1a的相对表达，我们在人外周血中鉴定了三种dc。表达CD1a和CD11c的主要群体被证明是表皮朗格汉斯细胞的直接前体。一小部分（CD1a-CD11c-）被鉴定为浆细胞样T细胞，被认为是淋巴系dc。5)未成熟树突状细胞将抗原内化到富含MHC II分子的溶酶体区室中。在树突状细胞分化过程中，富含MHC的溶酶体介导MHC ii肽复合物形成的能力受到严格控制，有助于协调抗原获取和炎症刺激与T细胞受体配体的形成。少

Antigen uptake, processing and presentation by dendritic cells (DCs) have become amenable to cell biological approaches. The critical events occur in DCs that are undergoing development and maturation in response to inflammatory stimuli. The aim of this project is to define developmental stages and to elucidate regulatory mechanisms of antigen processing in immunostimulatory dendritic cells. The following results are obtained.1) DCs ate unusually efficient at forming MHC-peptide complexes from phagocytosed cells, some 1-10 thousand times more efficiently than an exposure to preprocessed peptide. A comparable phenomenon is observed in vivo when short-lived migratory DCs migrate via afferent lymphatics to the T cell areas of the lymph nodes.2) After phagocytosing injected microspheres, about 25% of inflammatory monocytes migrated to the T area of draining node, where they expressed dendritic cell-restricted markers and high levels of costimulatory molecules.3) Fractalkine/neurotactin and … More MDC are isolated from mouse bone marrow-derived DC cDNA libraries by the signal sequence trap method. Both chemokines are expressed by DC differentiated from bone marrow precursors cells in vitro and mature DCs from tissues, and constitutively produced by DCs in T area to attract T cells.4) Based on the relative expression of CD11c and CD1a, we have identified three fractions of DCs in human peripheral blood. A major population expressing CD1a and CD11c is demonstrated to be immediate precursors of epidermal Langerhans cells. A minor fraction (CD1a-CD11c-) is identified as plasmacytoid T cells, which are supposed to be lymphoid-lineage DCs.5) Immature dendritic cells internalize antigens into lysosomal compartments rich in MHC II molecules. The capacity of MHC-rich lysosomes to mediate the formation of MHC II-peptide complexes is strictly controlled during dendritic cell differentiation, helping to coordinate antigen acquisition and inflammatory stimuli with formation of ligands for the T cell receptor. Less