title: Dissociation between skin test reactivity and anti-aeroallergen IgE: Determinants among urban Brazilian children.
abstract: BACKGROUND
  The dissociation between specific IgE and skin prick test reactivity to aeroallergens, a common finding in populations living in low and middle-income countries, has important implications for the diagnosis and treatment of allergic diseases. Few studies have investigated the determinants of this dissociation. In the present study, we explored potential factors explaining this dissociation in children living in an urban area of Northeast Brazil, focusing in particular on factors associated with poor hygiene.
  
  
  METHODS
  Of 1445 children from low income communities, investigated for risk factors of allergies, we studied 481 with specific IgE antibodies to any of Blomia tropicalis, Dermatophagoides pteronyssinus, Periplaneta americana and Blatella germanica allergens. Data on demographic, environmental and social exposures were collected by questionnaire; serum IgG and stool examinations were done to detect current or past infections with viral, bacterial, protozoan and intestinal helminth pathogens. We measured atopy by skin prick testing (SPT) and specific IgE (sIgE) to aerollergens in serum (by ImmunoCAP). SIgE reactivity to B. tropicalis extract depleted of carbohydrates was measured by an in-house ELISA. Total IgE was measured by in house capture ELISA. SNPs were typed using Illumina Omni 2.5.
  
  
  RESULTS
  Negative skin prick tests in the presence of specific IgE antibodies were frequent. Factors independently associated with a reduced frequency of positive skin prick tests were large number of siblings, the presence of IgG to herpes simplex virus, Ascaris lumbricoides and Trichuris trichiura infections, living in neighborhoods with infrequent garbage collection, presence of rodents and cats in the household and sIgE reactivity to glycosylated B. tropicalis allergens. Also, SNP on IGHE (rs61737468) was negatively associated with SPT reactivity.
  
  
  CONCLUSIONS
  A variety of factors were found to be associated with decreased frequency of SPT such as unhygienic living conditions, infections, total IgE, IgE response to glycosylated allergens and genetic polymorphisms, indicating that multiple mechanisms may be involved. Our data, showing that exposures to an unhygienic environment and childhood infections modulate immediate allergen skin test reactivity, provide support for the "hygiene hypothesis".
authors.affiliation: Instituto de Ciências da Saúde, Universidade Federal da Bahia, Salvador, Bahia, Brazil.
authors.forename: Neuza M
authors.identifier: http://orcid.org/0000-0002-2102-260X
authors.initials: NM
authors.lastname: Alcantara-Neves
authors.affiliation: Instituto de Ciências da Saúde, Universidade Federal da Bahia, Salvador, Bahia, Brazil.|Universidade Federal de Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil.
authors.forename: Rafael V
authors.initials: RV
authors.lastname: Veiga
authors.affiliation: Instituto de Ciências da Saúde, Universidade Federal da Bahia, Salvador, Bahia, Brazil.
authors.forename: João C M
authors.initials: JC
authors.lastname: Ponte
authors.affiliation: Departamento Medicina Social, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil.
authors.forename: Sérgio S
authors.initials: SS
authors.lastname: da Cunha
authors.affiliation: Departamento de Pediatria, Universidade Federal de Sergipe, Aracajú, Sergipe, Brazil.
authors.forename: Silvia M
authors.initials: SM
authors.lastname: Simões
authors.affiliation: ProAR- Núcleo de Excelência em Asma, Universidade Federal da Bahia, Salvador, Bahia, Brazil.
authors.forename: Álvaro A
authors.initials: ÁA
authors.lastname: Cruz
authors.affiliation: Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Maria
authors.initials: M
authors.lastname: Yazdanbakhsh
authors.affiliation: Instituto de Saúde Coletiva, Universidade Federal da Bahia, Salvador, Bahia, Brazil.
authors.forename: Sheila M
authors.initials: SM
authors.lastname: Matos
authors.affiliation: Instituto de Saúde Coletiva, Universidade Federal da Bahia, Salvador, Bahia, Brazil.|Departamento de Ciências Biológicas, Universidade Estadual do Sudoeste da Bahia, Vitória da Conquista, Bahia, Brazil.
authors.forename: Thiago Magalhães
authors.initials: TM
authors.lastname: Silva
authors.affiliation: Instituto de Ciências da Saúde, Universidade Federal da Bahia, Salvador, Bahia, Brazil.
authors.forename: Camila A
authors.initials: CA
authors.lastname: Figueiredo
authors.affiliation: Centro de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Salvador, Bahia, Brazil.
authors.forename: Lain C
authors.initials: LC
authors.lastname: Pontes-de-Carvalho
authors.affiliation: Institute of Infection and Immunity, St George's University of London, London, United Kingdom.
authors.forename: Laura C
authors.initials: LC
authors.lastname: Rodrigues
authors.affiliation: Departamento de Estatística, Instituto de Matemática, Universidade Federal da Bahia, Salvador, Bahia, Brazil.
authors.forename: Rosemeire L
authors.initials: RL
authors.lastname: Fiaccone
authors.affiliation: Faculty of Facultad de Ciencias Medicas, de la Salud y la Vida, Universidad Internacional del Ecuador, Quito, Ecuador.|Institute of Infection and Immunity, St George's University of London, London, United Kingdom.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Cooper
authors.affiliation: Instituto de Saúde Coletiva, Universidade Federal da Bahia, Salvador, Bahia, Brazil.
authors.forename: Maurício L
authors.initials: ML
authors.lastname: Barreto
mesh_terms: D000485:Allergens / Q000276:immunology*; D000818:Animals; D017164:Ascaris lumbricoides / Q000276:immunology; D001938:Brazil; D002415:Cats; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay; D005243:Feces / Q000382:microbiology / Q000469:parasitology / Q000821:virology; D006801:Humans; D006967:Hypersensitivity / Q000097:blood / Q000175:diagnosis / Q000276:immunology*; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology*; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D007139:Immunoglobulin epsilon-Chains / Q000235:genetics / Q000276:immunology; D020641:Polymorphism, Single Nucleotide / Q000276:immunology; D017455:Receptors, IgE / Q000235:genetics / Q000276:immunology; D012377:Rodentia; D018139:Simplexvirus / Q000276:immunology; D012882:Skin Tests / Q000379:methods*; D014258:Trichuris / Q000276:immunology; D014504:Urban Health / Q000706:statistics & numerical data
chemical_list: D000485:Allergens; C475664:FCER1A protein, human; D007074:Immunoglobulin G; D007139:Immunoglobulin epsilon-Chains; D017455:Receptors, IgE; D007073:Immunoglobulin E