Immune defense mechanisms of the dentin/pulp complex: Immunohistochemical analysis on the heterogeneity and kinetics of dendritic cells

本研究通过免疫组织化学和透射电镜观察牙髓炎和根尖周炎中树突状细胞（DC）亚群和共刺激分子表达细胞。(1)牙髓炎和根尖牙周炎诱导大鼠磨牙通过使未密封的牙髓曝光，和DC的动力学进行了研究，通过免疫电子显微镜的MHC II类分子，CD 11 c，CD 86和OX 62（标记大鼠DC亚群）。结果表明，正常牙周膜组织和根尖周病变组织中的DCs由两个亚群组成，不同亚群表达不同的CD 11 c和OX 62，且在谱系、成熟状态和功能上可能存在差异。在诱导根尖周病变，CD 86表达细胞，包括约10%的MHC II类分子表达细胞，经常分布在附近的神经纤维，表明参与成熟的DC神经相互作用的根尖周病变的发展。此外，在暴露的大鼠磨牙牙髓伤口愈合过程中的DCs动力学进行了研究后，1VITA帽，不断诱导牙髓愈合与牙本质桥的形成。结果表明，在暴露牙髓的初始愈合过程中，DC样细胞显示出在创面下的积聚。(2)免疫组化和电镜观察显示，表达BLA-DR的DCs主要分布在淋巴细胞丰富的区域。激光显微切割和RT-PCR分析表明，在淋巴细胞富集区，DC表面的CD 83和CD 86以及T淋巴细胞表面的CD 28表达上调。这些发现可能表明，DC作为抗原提呈细胞，刺激T淋巴细胞活化。

This study investigated dendritic cell (DC) subpopulations and co-stimulatory molecule-expressing cells in pulpitis and apical periodontitis by means of immunohistochemistry and transmission electron microscopy.(1) Pulpitis and apical periodontitis were induced in rat molars by making unsealed pulp exposures, and kinetics of DCs was investigated by means of immunoelectron microscopy for MHC class II molecules, CD11c, CD86 and OX62 (a marker for rat DC subpopulation). Results demonstrated that DCs in normal periodontal ligament and periapical lesions consisted of two subpopulations: the subpopulations differently expressed CD11c and OX62 and might differ in lineage, state of maturation and function. In the induced periapical lesions, CD86-expressing cells, comprising approximately 10% of MHC class II molecule-expressing cells, were frequently distributed in the vicinity of nerve fibers, suggesting the involvement of mature DC-nerve interaction in the development of periapical lesions. Moreover, kinetics of DCs during wound healing process of exposed rat molar pulps was investigated after 1VITA-capping, which constantly induced pulp healing with dentin bridge formation. It was demonstrated that DC-like cells showed an accumulation subjacent to the wound surface during initial healing process of the exposed pulps.(2) Immunohistochemistry and electron microscopy for human apical periodontitis revealed that DCs expressing BLA-DR were mainly distributed in lymphocyte-rich areas. By means of laser microdisection and RT-PCR analysis, it was demonstrated that upregulation of CD83 and CD86 on DCs and CD28 on T lymphocytes occurred in the lymphocyte-rich areas. These findings may indicate that DCs act as antigen presenting cells that stimulate T lymphocyte activation.