Distribution of myeloid dendritic cells and plasmacytoid dendritic cells in the synovial tissues of rheumatoid arthritis.
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.
Takakubo
Yuya
Y
Department of Orthopaedic Surgery, Yamagata University School of Medicine, and Yamagata Saisei Hospital, Yamagata, Japan. takakubo-y@med.id.yamagata-u.ac.jp
Takagi
Michiaki
M
Maeda
Kunihiko
K
Tamaki
Yasunobu
Y
Sasaki
Akiko
A
Asano
Tamon
T
Fukushima
Shigenobu
S
Kiyoshige
Yoshiro
Y
Orui
Hiroshi
H
Ogino
Toshihiko
T
Yamakawa
Mitsunori
M
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
D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase