Age-dependent T and B lymphocyte subsets defined by multicolor flow cytometry

Abstract Immune dysregulation in children due to primary immunodeficiency, autoimmune disease or immunomosuppressive therapy may be characterized in detail by multiparametric flow cytometry. To determine age-dependent reference values for healthy children, we developed four panels: aß and γδ T lymphocytes; regulatory T lymphocytes; B lymphocytes; NK and NK T cells. Detailed analyses performed on 18 healthy subjects aged 8 to 46 years revealed differences between adult and juvenile phenotypes in 66 of 301 distinct subsets. Among naïve aß T lymphocytes (CD45RA+CCR7+CD27+) we found a 60% decrease in the CD4+ subset but no change in the CD8+ subset in adults compared to children. Expression of CD31, an aß T lymphocyte marker of recent thymic emigration, decreased 50% with age. T regulatory cells (CD4+CD127loCD25+FoxP3+) were 30% lower in adults. No differences were found in major γδ T lymphocyte, NK, or NK T cell subsets. Memory B cells (CD38loCD24+) increased 2-fold with age, while naïve B cells (CD24hiCD38+IgM+IgD-) decreased by 50%. Thus, the influence of aging greatly effects subset frequencies, and may reflect decreasing thymus function and acute/chronic stimulation of memory B and T lymphocytes. Phenotypic analysis of leukocyte subsets may serve as a valuable tool for detecting and monitoring immune dysregulation in children, but age-matched controls are essential. Supported by the McMillen Foundation