Frequency and phenotypic analysis of CD4+CD25+ regulatory T cells in children with juvenile idiopathic arthritis.

BACKGROUND AND PURPOSE The aim of this study was to investigate the frequency of CD4(+)CD25(+) regulatory T cells and their phenotypic expression in peripheral blood of children with active and non-active juvenile idiopathic arthritis (JIA) and healthy controls, to determine if their frequency or phenotypic expression is involved in the immunoregulation of this disease. METHODS From October 2004 to October 2005, 55 JIA patients and 55 age- and gender-matched healthy controls were enrolled in the study at National Taiwan University Hospital. Flow cytometry was used to determine the frequency of CD4(+)CD25(+) and CD4(+)CD25(hi) in CD4(+) T cells and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) expression on CD4(+)CD25(+) by tricolor staining. Basic profiles, medication history, clinical symptoms and laboratory data were obtained by chart review and outpatient department interviews. RESULTS There was no significant difference in expression of CD4(+)CD25(+) T cells between patients with inactive JIA and normal controls (13.74+/-3.25% vs 12.85+/-3.68%, p>0.05). The expression of CD4(+)CD25(hi) T cells was significantly lower in inactive JIA patients than in normal controls (1.89+/-1.01% vs 2.76+/-1.28%, p<0.01). The expression of CTLA-4 on CD4(+)CD25(+) T cells was also significantly lower in inactive JIA patients compared with controls (4.37+/-2.02% vs 6.33+/-2.57%, p<0.001). CONCLUSION We speculate that a decreased frequency of CD4(+)CD25(hi) regulatory T cells and lower level of CTLA-4 expression on CD4(+)CD25(+) regulatory T cells might play a role in the immunoregulation of JIA.