title: Age- and infection-related maturation of the nasal immune response in 0-2-year-old children.
abstract: BACKGROUND
  The hygiene hypothesis suggests that exposure to micro-organisms influences development of the immune system in children.
  
  
  METHODS
  In this study, we examined nasal immune responses in the first 2 years of life in relation to age of children and the number of viral infections they have experienced. Nasal brushes were taken during rhinovirus- (n = 20) or respiratory syncytial virus (RSV)-induced (n = 7) upper respiratory tract infections (URTI), and of controls (n = 40).
  
  
  RESULTS
  The number of macrophages were higher during URTI and increased with age. The number of T lymphocytes increased with age in controls and were higher during URTI at all ages. We found an age-related decrease in the number of interleukin (IL)-4- and IL-10-positive cells in controls, while the number of IL-12-positive cells remained unchanged. Changes in T lymphocyte and IL-4 cell number were stronger related to the age of the child than to the number of respiratory infections, while the opposite was true for macrophages.
  
  
  CONCLUSIONS
  In infants, we found an infection- and age-related increase respectively for nasal macrophages and T lymphocytes during URTI. Furthermore, the number of IL-4- and IL-10-positive cells decreased with age. Whether this maturation reflects a natural age-related maturation, the degree of exposure to respiratory infections, or possibly both, could not be resolved and needs further study.
authors.affiliation: Department of Otorhinolaryngology, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: I J
authors.initials: IJ
authors.lastname: van Benten
authors.forename: C M
authors.initials: CM
authors.lastname: van Drunen
authors.forename: L P
authors.initials: LP
authors.lastname: Koopman
authors.forename: B C
authors.initials: BC
authors.lastname: van Middelkoop
authors.forename: W C J
authors.initials: WC
authors.lastname: Hop
authors.forename: A D M E
authors.initials: AD
authors.lastname: Osterhaus
authors.forename: H J
authors.initials: HJ
authors.lastname: Neijens
authors.forename: W J
authors.initials: WJ
authors.lastname: Fokkens
mesh_terms: D017677:Age Distribution; D000375:Aging / Q000276:immunology* / Q000378:metabolism; D000917:Antibody Formation; D016022:Case-Control Studies; D015331:Cohort Studies; D016207:Cytokines / Q000378:metabolism; D005260:Female; D006801:Humans; D007107:Immune System / Q000254:growth & development; D007223:Infant; D007231:Infant, Newborn; D007239:Infections; D008264:Macrophages / Q000473:pathology; D008297:Male; D009296:Nasal Cavity / Q000276:immunology* / Q000473:pathology; D010850:Picornaviridae Infections / Q000453:epidemiology / Q000276:immunology* / Q000473:pathology; D018357:Respiratory Syncytial Virus Infections / Q000453:epidemiology / Q000276:immunology* / Q000473:pathology; D012141:Respiratory Tract Infections / Q000453:epidemiology / Q000276:immunology* / Q000473:pathology; D012229:Rhinovirus; D013601:T-Lymphocytes / Q000473:pathology
chemical_list: D016207:Cytokines