title: Frequency of lower respiratory tract infections in relation to adaptive immunity in children with Down syndrome compared to their healthy siblings.
abstract: OBJECTIVE
  Children with Down syndrome (DS) experience respiratory tract infections (RTIs) more frequently than healthy children. We investigated whether this is related to different immunological characteristics associated with DS.
  
  
  METHODS
  The study group consisted of 22 children with DS and 22 of their healthy, age-range matched siblings. Data were collected on infections and hospitalizations because of lower RTIs. Immunoglobulin and IgG subclass levels in blood, as well as lymphocyte and T cell (subset) counts, were determined.
  
  
  RESULTS
  The children with DS had a significantly higher frequency of lower RTIs and related hospitalization than their siblings. We also found significantly reduced IgG2 levels as well as significantly lower counts of total lymphocytes, CD4(+) T lymphocytes, CD4(+) invariant natural killer (iNKT) cells and regulatory T cells in the DS group.
  
  
  CONCLUSIONS
  In children with DS, reduced levels of IgG2, total lymphocytes, T lymphocytes, iNKT cells and regulatory T cells might contribute to their higher susceptibility to lower RTIs.
authors.affiliation: Department of Pediatrics, VU University Medical Center, Amsterdam, The Netherlands. ingemar.swenne@akademiska.se
authors.forename: Chantal J M
authors.initials: CJ
authors.lastname: Broers
authors.forename: Reinoud J B J
authors.initials: RJ
authors.lastname: Gemke
authors.forename: Michel E
authors.initials: ME
authors.lastname: Weijerman
authors.forename: Dirk-J
authors.initials: DJ
authors.lastname: Kuik
authors.forename: Ingrid M W
authors.initials: IM
authors.lastname: van Hoogstraten
authors.forename: A Marceline
authors.initials: AM
authors.lastname: van Furth
mesh_terms: D056704:Adaptive Immunity; D015415:Biomarkers / Q000097:blood; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism; D016022:Case-Control Studies; D002648:Child; D004314:Down Syndrome / Q000150:complications / Q000276:immunology*; D005260:Female; D006330:Heart Defects, Congenital / Q000150:complications / Q000276:immunology; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D018655:Lymphocyte Count; D008297:Male; D055611:Natural Killer T-Cells / Q000378:metabolism; D012141:Respiratory Tract Infections / Q000150:complications / Q000453:epidemiology / Q000276:immunology*; D035781:Siblings
chemical_list: D015415:Biomarkers; D007074:Immunoglobulin G