title: The indoor air and asthma:  the role of cat allergens.
abstract: OBJECTIVE
  The objective is to discuss recent progress in our understanding of the role of the indoor environment in asthma, focusing on the special role of cat allergens.
  
  
  RESULTS
  Sensitization to Fel d 1 is the dominant event in inhalant responses to cat; however, there are also IgE responses to the lipocalin (Fel d 4), to cat albumin (Fel d 2), and to the oligosaccharide galactose-alpha-1,3-galactose (alpha-gal) on cat IgA (Fel d 5w) and other molecules. The dose response and routes of sensitization for these allergens are now thought to be diverse. It is important to remember that exposure outside a house with a cat is sufficient to cause sensitization. Furthermore, the only solid evidence about a role in asthma relates to Fel d 1. Recently, it has been shown that tolerance associated with early exposure to cats can persist to age 18 and that IgE to alpha-gal (on cat IgA) is not related to asthma. In addition, a recent study of anti-IgE reinforces the evidence that IgE antibodies to indoor allergens make a major contribution to asthma severity.
  
  
  CONCLUSIONS
  Exposure to Fel d 1 in a home with a cat is far higher than the levels necessary to induce an allergic (IgE antibody) response. In keeping with that, children may develop tolerance, which can be long-lived. In addition, there is increasing evidence that IgE antibodies to an inhalant allergen, such as Fel d 1, dust mite, or cockroach, are causally related to lung inflammation and asthma.
authors.affiliation: University of Virginia Asthma and Allergic Diseases Center, University of Virginia Health System, Charlottesville, VA 22908, USA.
authors.forename: Libby A
authors.initials: LA
authors.lastname: Kelly
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Erwin
authors.forename: Thomas A E
authors.initials: TA
authors.lastname: Platts-Mills
mesh_terms: D016902:Air Pollution, Indoor; D000485:Allergens; D000818:Animals; D052179:Antigens, Plant / Q000276:immunology; D001249:Asthma / Q000453:epidemiology / Q000209:etiology / Q000276:immunology*; D002415:Cats; D003058:Cockroaches / Q000276:immunology; D004391:Dust / Q000276:immunology; D004781:Environmental Exposure; D006023:Glycoproteins / Q000276:immunology*; D006798:Housing; D006801:Humans; D006967:Hypersensitivity / Q000209:etiology* / Q000276:immunology; D007073:Immunoglobulin E / Q000276:immunology*; D054834:Lipocalins; D008925:Mites / Q000276:immunology; D012709:Serum Albumin / Q000276:immunology
chemical_list: D000485:Allergens; D052179:Antigens, Plant; D004391:Dust; C522889:Fel d 2 allergen, Felis domesticus; C499337:Fel d 4 allergen, Felis domesticus; D006023:Glycoproteins; D054834:Lipocalins; D012709:Serum Albumin; D007073:Immunoglobulin E; C059296:Fel d 1 protein, Felis domesticus
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