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RESEARCH REPORT |
1 Pulp Biology and Endodontics, Graduate School, Tokyo Medical and Dental University, Yushima 1-5-45, Bunkyo-Ku, Tokyo, 113-8549, Japan;
2 Cariology, Restorative Sciences, and Endodontics, School of Dentistry, University of Michigan, Ann Arbor, MI, USA; and
3 Division of Cariology, Operative Dentistry and Endodontics, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
* corresponding author, tomoendo{at}tmd.ac.jp
Substantial numbers of dendritic cells have been detected in radicular granulomas. To test the hypothesis that local antigen presentation from dendritic cells to T-cells is involved critically in immunological responses within radicular granulomas, we compared characteristics of dendritic cells and macrophages by morphological and biological analyses. Under light microscopy, HLA-DR+ and CD68+ cells showed diverse profiles, including dendritic-shaped cells. Transmission electron microscopy revealed that HLA-DR+ dendritic cells, with long cytoplasmic processes and lacking distinct phagosomes, were concentrated in the lymphocyte-rich area. HLA-DR alpha-chain, CD83, and CD86 mRNAs from HLA-DR+ dendritic cells, and CD28 mRNA from CD28+ T-cells were up-regulated in lymphocyte-rich area. Scanning electron microscopy demonstrated that the density of gold particles on dendritic cells was higher than that on HLA-DR+ macrophages. These results suggest that dendritic cells in radicular granulomas are associated with local defense reactions as stronger antigen-presenting cells, as compared with macrophages.
KEY WORDS: dendritic cell HLA-DR transmission electron microscopy scanning electron microscopy macrophage
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