Distribution and clinical significance of blood dendritic cells in children with juvenile idiopathic arthritis.

BACKGROUND: A role for dendritic cells (DC) in the development of adult rheumatoid arthritis has been suggested. To date, this problem has been poorly explored in juvenile idiopathic arthritis (JIA). OBJECTIVE: To analyse 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 47 untreated children with JIA and 32 healthy controls. Moreover, BDC were investigated in JIA synovial fluid (SF). When the panel of monoclonal antibodies against BDC antigens (BDCA) was used, three BDC subpopulations were determined: myeloid type 1 (mDC1; BDCA-1+/HLA-DR+/CD19-), myeloid type 2 (mDC2; BDCA-3+/HLA-DR+/CD14-) and plasmacytoid (pDC; BDCA-2+/HLA-DR+/CD123+). RESULTS: A considerable deficiency of all subtypes of BDC was found in the PB of children with JIA. BDC counts in JIA SF were significantly higher than in PB both from children with JIA (p<0.001) 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. A smaller number of PB BDC at diagnosis correlated significantly with poor response to treatment. CONCLUSIONS: A deficiency of BDC in PB is accompanied by enrichment of SF with those cells. Probably, circulating BDC migrate to joints where they undergo maturation and help to mediate and maintain the local immune response. Interestingly, the level of PD BDC deficiency seems to influence the outcome in children with JIA.

Apoptosis of peripheral blood lymphocytes in patients with juvenile idiopathic arthritis.

BACKGROUND: Recent data suggested that abnormalities in mechanisms regulating apoptosis may have a role in the development of the rheumatoid process. OBJECTIVE: To evaluate different aspects of apoptosis in children with juvenile idiopathic arthritis (JIA). METHODS: The frequency of TUNEL positive peripheral blood (PB) lymphocytes (apoptotic index (AI)), as well as serum CD95 (APO1/Fas) antigen expression and serum levels of sFas and interleukin 15 (IL15), were examined in 44 cases of JIA. Results were correlated with type of onset, activity of JIA, and acute phase indicators. RESULTS: The AI of lymphocytes was significantly higher in patients with JIA than in controls (p=0.020). The mean AI of lymphocytes was increased in JIA with systemic type of onset and high activity (p=0.001). Moreover, IL15 levels in systemic disease were higher than in controls (p=0.012). An increased AI correlated with raised IL15 (p=0.046), erythrocyte sedimentation rate (p=0.005) and C reactive protein (CRP; p=0.017). Additionally, correlation was found between IL15 and CRP levels (p=0.039). CD95 and sFas levels were unchanged compared with controls. CONCLUSION: PB lymphocytes of children with JIA have an increased tendency to undergo apoptosis. The degree of apoptosis depends on the type of onset and activity of JIA and correlates with serum levels of IL15. Further studies are needed to explain whether this is an epiphenomenon of the disease activity or is related to the pathogenesis of JIA.