Cross-sectional study on allergic sensitization of Austrian adolescents using molecule-based IgE profiling.

BACKGROUND: Allergen-specific IgE antibodies are a hallmark of type I allergy. The aim of this cross-sectional study was to analyze the sensitization profiles of an Austrian adolescent population utilizing molecule-based IgE diagnosis. METHODS: Serum samples of 501 nonselected pupils from Salzburg, Austria, were tested in ImmunoCAP ISAC® for IgE reactivity to 112 single allergens. Sensitization profiles were assessed and statistically coordinated with reported allergies. RESULTS: In the population aged 12-21 years, 53.5% showed IgE reactivity to at least one allergen tested. The highest prevalence was found for Phl p 1 from grass pollen (26.5%), group 2 mite allergens (18.2%), Bet v 1 from birch pollen (16.3%) and Fel d 1 from cat (14.4%). The majority of participants showed a complex sensitization profile and reacted on average to 9 allergens. Pollen sensitization was highly prevalent (41.7%) and mainly driven by group I grass and PR-10 allergens of the Betulaceae family, while Pla l 1 represented the most relevant weed. Diagnosed and self-reported allergies were noted in 21.9% and 45.5% of participants, respectively, and correlated well with in vitro results. Among atopic individuals, 71.4% reported to suffer from at least one allergy; concordance was found for grass and cat sensitization, while venom- and weed pollen-positive individuals were frequently asymptomatic. CONCLUSIONS: More than half of the tested adolescent population had already established an atopic status presenting a complex IgE reactivity profile dominated by pollen sensitization. Detailed molecule-based analysis allows determining relevant biomarkers and monitoring of the atopic status in populations.

IgE autoantibodies against the intracellular domain of BP180.

BACKGROUND: Bullous pemphigoid (BP) is an autoimmune subepidermal blistering disease characterized by autoantibodies against the hemidesmosomal proteins BP180 (type XVII collagen) and BP230. BP not only involves IgG-mediated neutrophil activation, leading to blistering, but also IgE-dependent activation of mast cells and basophils. While IgG and IgE autoantibodies target the extracellular noncollagenous (NC) 16A domain of BP180, little is known whether other BP180 regions are targeted by these antibody classes. OBJECTIVES: To characterize IgE and IgG autoantibody binding to antigenic sites on the intracellular domain (ICD) of BP180 compared with BP180 NC16A. METHODS: IgE/IgG autoreactivity against recombinant BP180 ICD and NC16A was determined by immunoblotting of sera from 18 patients with BP and 10 controls. RESULTS: Total serum IgE was elevated in 16 of 18 BP sera. Most BP sera tested positive (15 of 18) to NC16A with both immunoglobulin classes. Additionally, 14 of 18 sera showed IgE reactivity with an epitope mapped to the ICD of BP180 (amino acid residues 103-266). Mapping of ICD antigenic sites revealed similar IgE and IgG reactivities for most regions except for greater IgE reactivity to amino acid residues 234-398 (11 of 18 BP sera) than IgG (five of 18). Control sera failed to display IgE reactivity to these antigens. CONCLUSIONS: The results indicate that BP180 NC16A is not the only antigenic determinant of IgE autoantibodies in BP and that additional, novel epitopes exist on different regions of the ICD of BP180. The heterogeneous autoimmune response against BP180 suggests intramolecular epitope spreading during disease progression.