title: Peanut sensitization during the first 5 yr of life is associated with elevated levels of peanut-specific IgG.
abstract: BACKGROUND
  Allergen-specific IgE antibodies are implicated in allergic diseases while allergen-specific IgG antibodies have been proposed to prevent allergic reactions. The objective for this study was to study whether the immune response (IgG and IgG4) to peanut differs in IgE-sensitized and non-sensitized young children.
  
  
  METHODS
  A total of 239 children have been followed prospectively from birth to 5 yr of age. The levels of IgG and IgG4 to peanut, Ara h 2, and Ara h 8 were analyzed at 2 and 5 yr of age and related to IgE sensitization and peanut consumption.
  
  
  RESULTS
  The levels of peanut-specific IgG and IgG4 were significantly higher in peanut-sensitized children at 2 and 5 yr of age when compared with non-sensitized children and children sensitized to other food/inhalant allergens. A strong correlation was seen between levels of peanut-specific IgG/IgG4-ratios and peanut-specific IgE at 5 yr of age. Children avoiding peanuts, a subgroup of the peanut sensitized, had statistically significant higher levels of IgE to peanut and a tendency of higher IgG and IgG4 levels to peanut. In the avoidance group, significant correlations between IgE and IgG/IgG4 to peanut were found compared with children eating peanuts.
  
  
  CONCLUSIONS
  Peanut-specific IgG or IgG4 levels were elevated in peanut-sensitized children especially those avoiding peanuts. In our study, IgG and IgG4 do not seem to indicate tolerance or protection from sensitization.
authors.affiliation: Department of Immunology, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.
authors.forename: E
authors.initials: E
authors.lastname: Sverremark-Ekström
authors.forename: E H
authors.initials: EH
authors.lastname: Hultgren
authors.forename: M P
authors.initials: MP
authors.lastname: Borres
authors.forename: C
authors.initials: C
authors.lastname: Nilsson
mesh_terms: D055516:2S Albumins, Plant / Q000276:immunology*; D000918:Antibody Specificity; D052179:Antigens, Plant / Q000276:immunology*; D010367:Arachis / Q000276:immunology*; D002675:Child, Preschool; D005260:Female; D006023:Glycoproteins / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology; D007074:Immunoglobulin G / Q000097:blood* / Q000276:immunology; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D021183:Peanut Hypersensitivity / Q000209:etiology / Q000276:immunology*; D012882:Skin Tests
chemical_list: D055516:2S Albumins, Plant; D052179:Antigens, Plant; C500890:Ara h 2 allergen, Arachis hypogaea; D006023:Glycoproteins; D007074:Immunoglobulin G; D007073:Immunoglobulin E