title: Immediate skin reactivity to histamine and to allergens in cohorts of 9-year-old schoolchildren studied 16 years apart.
abstract: BACKGROUND
  Differing or increasing prevalence of positive allergen skin-prick tests observed in Europe could at least in part be explained by population changes in histamine skin reactivity. These changes would also alter the relationship between positive allergen skin-prick tests and serum IgE.
  
  
  OBJECTIVE
  To assess changes in histamine reactivity, allergen skin-prick tests and serum IgE in our geographical setting.
  
  
  METHODS
  We compared the outcome of two epidemiological surveys conducted 16 years apart in unselected 9-year-old schoolchildren (170 in 1983 and 176 in 1999) from a semi-rural region in central Italy. Outcome measures were skin-prick tests with two histamine concentrations (10 and 1 mg/mL) and 11 locally relevant allergens; serum total and specific IgE for positive allergens.
  
  
  RESULTS
  The two histamine concentrations induced significantly larger mean weal diameters in 1999 than in 1983 (10 mg/mL: 5.28+/-0.82 mm vs. 3.25+/-0.97 mm; P<0.001). Whereas the prevalence of subjects with at least one positive allergen-induced weal reaction (>or=3 mm) increased over the 16 years (from 15.3% in 1983 to 25.6% in 1999), the prevalence of positive skin-prick tests, expressed as the allergen/ histamine weal ratio, remained almost unchanged. A given allergen weal diameter yielded less total (P<0.05 by Student's t-test for cumulative weals <8 mm) and specific (P<0.01 by Student's t-test for weals <3 mm, P<0.05 by Kruskal-Wallis test) serum IgE in 1999 than in 1983.
  
  
  CONCLUSIONS
  Although the causes and mechanisms remain unclear, the increased histamine skin reactivity over time is associated with an increase in positive allergen skin-prick tests. In the presence of increased tissue and organ susceptibility to histamine, minute amounts of specific IgE could have important biological consequences.
authors.affiliation: Department of Pediatrics, Second School of Medicine, University La Sapienza, Rome, Italy. ronchetti@uniroma1.it
authors.forename: R
authors.initials: R
authors.lastname: Ronchetti
authors.forename: M P
authors.initials: MP
authors.lastname: Villa
authors.forename: J
authors.initials: J
authors.lastname: Pagani
authors.forename: S
authors.initials: S
authors.lastname: Martella
authors.forename: F
authors.initials: F
authors.lastname: Guglielmi
authors.forename: B
authors.initials: B
authors.lastname: Paggi
authors.forename: Z
authors.initials: Z
authors.lastname: Bohmerova
authors.forename: C
authors.initials: C
authors.lastname: Falasca
authors.forename: M
authors.initials: M
authors.lastname: Barreto
mesh_terms: D000485:Allergens / Q000276:immunology*; D000528:Alternaria / Q000276:immunology; D000818:Animals; D039741:Antigens, Dermatophagoides / Q000276:immunology; D001230:Aspergillus / Q000276:immunology; D002415:Cats; D002648:Child; D005260:Female; D006632:Histamine / Q000276:immunology*; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000453:epidemiology* / Q000276:immunology / Q000473:pathology; D007073:Immunoglobulin E / Q000097:blood*; D007558:Italy / Q000453:epidemiology; D008297:Male; D031658:Olea / Q000276:immunology; D032403:Parietaria / Q000276:immunology; D031785:Poa / Q000276:immunology; D015995:Prevalence; D012423:Rural Health; D012867:Skin / Q000276:immunology* / Q000473:pathology; D012882:Skin Tests / Q000379:methods
chemical_list: D000485:Allergens; D039741:Antigens, Dermatophagoides; D007073:Immunoglobulin E; D006632:Histamine