title: Immune responses to birch in young children during their first 7 years of life.
abstract: BACKGROUND
  The character of immune responses to allergens during the first years of life may decide whether the individual will become tolerant or develop allergy later in life.
  
  
  OBJECTIVE
  To study the development of immune responses to the seasonal inhalant allergen birch over the first 7 years of life.
  
  
  METHODS
  Blood samples were obtained from 21 children who were followed prospectively from the second to the seventh pollen season of life. Birch-induced cytokine production and IgG subclass antibodies to rBet v 1 were analysed with ELISA, mRNA expression with real time PCR, IgE antibodies to birch with Magic Lite and birch-induced mononuclear cell proliferation with 3H-thymidine incorporation.
  
  
  RESULTS
  Birch-induced IFN-gamma and IL-10 production increased with age, both in atopic and non-atopic children, while birch-induced IL-13 production decreased. The two children who were sensitized and developed clinical allergy to birch showed persistent IL-4 and IL-5 production and IL-9 mRNA expression, as well as Th2-associated IgG4 responses. Transient Th2-like responses were observed among the other children. Proliferative responses and IgG1 antibodies were seen in all children.
  
  
  CONCLUSIONS
  Immune responses to birch can be demonstrated in all children, during the first 7 years of life, regardless of atopic status. A transient early Th2-like response is down-regulated after the fourth pollen season, except in children who develop clinical allergy to the particular allergen.
authors.affiliation: Department of Molecular and Clinical Medicine, Division of Pediatrics, and Clinical Research Centre Faculty of Health Sciences, Linköping University, Linköping, Sweden. malfa@kfc.liu.se
authors.forename: M F
authors.initials: MF
authors.lastname: Böttcher
authors.forename: M C
authors.initials: MC
authors.lastname: Jenmalm
authors.forename: B
authors.initials: B
authors.lastname: Björkstén
mesh_terms: D000375:Aging / Q000276:immunology*; D000485:Allergens / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D003876:Dermatitis, Atopic; D015536:Down-Regulation; D005260:Female; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000276:immunology*; D007073:Immunoglobulin E / Q000097:blood; D007223:Infant; D007231:Infant, Newborn; D007371:Interferon-gamma / Q000096:biosynthesis; D007378:Interleukins / Q000096:biosynthesis; D008297:Male; D011058:Pollen / Q000276:immunology*; D016133:Polymerase Chain Reaction / Q000379:methods; D011446:Prospective Studies; D006255:Rhinitis, Allergic, Seasonal / Q000209:etiology / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology; D014197:Trees / Q000276:immunology*
chemical_list: D000485:Allergens; D007378:Interleukins; D007073:Immunoglobulin E; D007371:Interferon-gamma