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+CD25hi 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 +CD25hi 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+CD25hi 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. ? 2008 Journal of Microbiology, Immunology and Infection.