title: Quantitative, Phenotypical, and Functional Characterization of Cellular Immunity in Children and Adolescents With Down Syndrome.
abstract: Infections and autoimmune disorders are more frequent in Down syndrome, suggesting abnormality of adaptive immunity. Although the role of B cells and antibodies is well characterized, knowledge regarding T cells is limited.
  
  
  
  Lymphocyte subpopulations of 40 children and adolescents with Down syndrome and 51 controls were quantified, and phenotype and functionality of antigen-specific effector T cells were analyzed with flow cytometry after polyclonal and pathogen-specific stimulation (with varicella-zoster virus [VZV] and cytomegalovirus [CMV]). Results were correlated with immunoglobulin (Ig) G responses.
  
  
  
  Apart from general alterations in the percentage of lymphocytes, regulatory T cells, and T-helper 1 and 17 cells, all major T-cell subpopulations showed higher expression of the inhibitory receptor PD-1. Polyclonally stimulated effector CD4+ T-cell frequencies were significantly higher in subjects with Down syndrome, whereas their inhibitory receptor expression (programmed cell death 1 [PD-1] and cytotoxic T-lymphocyte antigen 4 [CTLA-4]) was similar to that of controls and cytokine expression profiles were only marginally altered. Pathogen-specific immunity showed age-appropriate levels of endemic infection, with correlation of CMV-specific cellular and humoral immunity in all subjects. Among VZV IgG-positive individuals, a higher percentage of VZV-specific T-cell-positive subjects was seen in those with Down syndrome.
  
  
  
  Despite alterations in lymphocyte subpopulations, individuals with Down syndrome can mount effector T-cell responses with similar phenotype and functionality as controls but may require higher effector T-cell frequencies to ensure pathogen control.
authors.affiliation: Departments of Transplant and Infection Immunology.
authors.forename: Justine
authors.initials: J
authors.lastname: Schoch
authors.affiliation: Pediatrics and Neonatology.
authors.forename: Tilman R
authors.initials: TR
authors.lastname: Rohrer
authors.affiliation: Pediatric Cardiology, and.
authors.forename: Michael
authors.initials: M
authors.lastname: Kaestner
authors.affiliation: Pediatric Cardiology, and.
authors.forename: Hashim
authors.initials: H
authors.lastname: Abdul-Khaliq
authors.affiliation: Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Austria.
authors.forename: Ludwig
authors.initials: L
authors.lastname: Gortner
authors.affiliation: Internal Medicine IV, Saarland University, Homburg, Germany; and.
authors.forename: Urban
authors.initials: U
authors.lastname: Sester
authors.affiliation: Departments of Transplant and Infection Immunology.
authors.forename: Martina
authors.initials: M
authors.lastname: Sester
authors.affiliation: Departments of Transplant and Infection Immunology.
authors.forename: Tina
authors.initials: T
authors.lastname: Schmidt
mesh_terms: D000293:Adolescent; D000914:Antibodies, Viral / Q000097:blood / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D016022:Case-Control Studies; D002648:Child; D003587:Cytomegalovirus / Q000276:immunology; D004314:Down Syndrome / Q000276:immunology*; D005260:Female; D014645:Herpesvirus 3, Human / Q000276:immunology; D006801:Humans; D007111:Immunity, Cellular / Q000276:immunology*; D008297:Male; D010641:Phenotype
chemical_list: D000914:Antibodies, Viral
keywords: Down syndrome; cellular immunity; immunodeficiency disorders.; trisomy 21