Objectives: The role of dendritic cells (DC) in the development of adult rheumatoid arthritis has been suggested. So far, this problem was poorly explored in juvenile idiopathic arthritis (JIA). In this study we analyzed distribution and maturation status of blood DC (BDC) in JIA.
Methods: Absolute BDC counts were assessed by the “single platform” method in peripheral blood (PB) of 47untreated JIA children and 32 healthy controls. Moreover, BDC were investigated in JIA synovial fluid (SF). Using the panel of monoclonal antibodies against BDC antigens (BDCA), three BDC subpopulations were determined: myeloid type 1 (mDC1; BDCA1+/HLA-DR+/CD19-), myeloid type 2 (mDC2; BDCA3+/HLA-DR+/CD14-) and plasmacytoid (pDC; BDCA2+/HLA-DR+/CD123+).
Results: We found the profound deficiency of all subtypes of BDC in PB of JIA children. Moreover, BDC counts in JIA SF were significantly higher than in PB from both JIA (p<0.0001) and healthy children (p<0.001). SF BDC, especially mDC1 and mDC2 subtypes, had significantly higher expression of maturation markers (CD40, CD80, CD86 or CD83 antigens) than those from PB. Moreover, lower PB BDC number at diagnosis correlated significantly with poor response to treatment.
Conclusions: This is the first study giving the referential data on particular PB and SF BDC subtypes in JIA. Deficiency of BDC in PB is accompanied by SF enrichment with those cells. Probably, circulating BDC migrate to joints where undergo maturation and participate in mediation and maintaining local immune response. Interestingly, the level of PD BDC deficiency seems to influence the outcome in JIA children.
- dendritic cells
- juvenile idiopathic arthritis
- maturation markers
- peripheral blood
- synovial fluid