Thymopoiesis and regulatory T cells in healthy children and adolescents

• Autor(a) principal: Arismendi, Maria Izabel
• Data de Publicação: 2012
• Outros Autores: Kallas, Esper Georges [UNIFESP], Santos, Bianca Almeida Natali dos, Carneiro-Sampaio, Magda Maria Sales, Kayser, Cristiane [UNIFESP]
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNIFESP
• dARK ID: ark:/48912/001300000q33n
• DOI: 10.6061/clinics/2012(05)04
• Texto Completo: http://dx.doi.org/10.6061/clinics/2012(05)04; http://repositorio.unifesp.br/handle/11600/6806
• topic: T lymphocytes; Thymus; Foxp3; T-cell Receptor

OBJECTIVES: The purpose of this study was to investigate the association between T cell receptor excision circle levels in peripheral blood mononuclear cells and regulatory T cells that co-express CD25 and Foxp3 in healthy children and adolescents of different ages. MATERIALS AND METHODS: The quantification of signal-joint T-cell receptor excision circle levels in the genomic DNA of peripheral blood mononuclear cells was performed using real-time quantitative PCR. The analysis of CD4, CD8, CD25, and Foxp3 expression was performed using flow cytometry. RESULTS: Ninety-five healthy controls (46 females and 49 males) ranging in age from 1 to 18 years were analyzed. The mean T-cell receptor excision circle count in all individuals was 89.095¡36.790 T-cell receptor excision circles per microgram of DNA. There was an inverse correlation between T-cell receptor excision circles counts and age (r = -0.846; p<0.001) as well as between the proportion of CD4+CD25+Foxp3+ T cells and age (r = -0.467; p = 0.04). In addition, we observed a positive correlation between the amount of CD4+CD25+Foxp3+ T cells and the amount of Tcell receptor excision circles per microgram of DNA in individuals of all ages (r = -0.529; p = 0.02). CONCLUSIONS: In this study, we observed a decrease in the thymic function with age based on the fact that the level of T-cell receptor excision circles in the peripheral blood positively correlated with the proportion of regulatory T cells in healthy children and adolescents. These findings indicate that although T-cell receptor excision circles and regulatory T cells levels decrease with age, homeostasis of the immune system and relative regulatory T cells population levels are maintained in the peripheral blood.