title: Distribution of myeloid dendritic cells and plasmacytoid dendritic cells in the synovial tissues of rheumatoid arthritis.
abstract: OBJECTIVE
  To examine the precise tissue distribution of dendritic cells (DC) and indoleamine 2,3-dioxygenase (IDO)-expressing cells in synovial tissue and synovial fluid (SF) from patients with rheumatoid arthritis (RA) and osteoarthritis (OA).
  
  
  METHODS
  Synovial tissues from 30 patients with RA and 7 with OA were immunohistochemically stained for DC markers. The examined areas were classified into 5 categories based on pathobiological staging and histopathological grading systems. Myeloid DC (mDC) and plasmacytoid DC (pDC) were isolated using positive and negative magnetic sorting systems, respectively, from SF samples (7 patients with RA and 4 with OA) and synovial tissues (3 RA, 4 OA).
  
  
  RESULTS
  mDC were mainly observed in lymphoid aggregations. pDC were scattered around perivenular infiltration areas, and small and large lymphoid aggregations in RA. The mDC/pDC ratio increased significantly, with higher grading in RA SF tissues compared to OA synovial tissues (p<0.05). IDO-immunoreactivity was detected in pDC by serial sectioning and staining of RA synovial tissues.
  
  
  CONCLUSIONS
  Our results indicate that mature mDC play a central role in the RA inflammatory process. Although there were fewer pDC than mDC, the presence of IDO-positive pDC suggests a possible tolerance mechanism in RA synovial tissues. However, it is probably modest due to the marked inflammation in RA, in which mDC are dominant.
authors.affiliation: Department of Orthopaedic Surgery, Yamagata University School of Medicine, and Yamagata Saisei Hospital, Yamagata, Japan. takakubo-y@med.id.yamagata-u.ac.jp
authors.forename: Yuya
authors.initials: Y
authors.lastname: Takakubo
authors.forename: Michiaki
authors.initials: M
authors.lastname: Takagi
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Maeda
authors.forename: Yasunobu
authors.initials: Y
authors.lastname: Tamaki
authors.forename: Akiko
authors.initials: A
authors.lastname: Sasaki
authors.forename: Tamon
authors.initials: T
authors.lastname: Asano
authors.forename: Shigenobu
authors.initials: S
authors.lastname: Fukushima
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Kiyoshige
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Orui
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Ogino
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Yamakawa
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000276:immunology / Q000473:pathology*; D016022:Case-Control Studies; D003713:Dendritic Cells / Q000276:immunology* / Q000378:metabolism; D005260:Female; D006801:Humans; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000276:immunology / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D022423:Myeloid Cells / Q000276:immunology*; D010003:Osteoarthritis / Q000473:pathology; D013582:Synovial Fluid / Q000276:immunology*; D013583:Synovial Membrane / Q000276:immunology* / Q000473:pathology
chemical_list: D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase