Thymopoiesis and regulatory T cells in healthy children and adolescents

Clinics (Sao Paulo). 2012;67(5):425-9. doi: 10.6061/clinics/2012(05)04.

Abstract

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 T-cell 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Age Factors
  • Autoimmune Diseases / immunology*
  • CD4 Antigens / analysis
  • CD4 Lymphocyte Count
  • CD8 Antigens / analysis
  • Child
  • Child, Preschool
  • Female
  • Forkhead Transcription Factors / analysis*
  • Humans
  • Infant
  • Interleukin-2 Receptor alpha Subunit / analysis*
  • Male
  • Receptors, Antigen, T-Cell / metabolism
  • T-Lymphocytes, Regulatory / immunology*
  • T-Lymphocytes, Regulatory / metabolism
  • Thymus Gland / immunology*
  • Thymus Gland / metabolism

Substances

  • CD4 Antigens
  • CD8 Antigens
  • FOXP3 protein, human
  • Forkhead Transcription Factors
  • IL2RA protein, human
  • Interleukin-2 Receptor alpha Subunit
  • Receptors, Antigen, T-Cell