title: Airborne endotoxin exposure and the development of airway antigen-specific allergic responses.
abstract: OBJECTIVE
  Repeated exposure of aerosolized antigen via respiratory tract can induce immunoglobulin (Ig) E isotype-specific tolerance to this antigen. However, the atopic individuals often produce a higher titre of IgE in response to airborne environmental allergens. The mechanisms of this differential regulation of airway allergen-specific immune responses are not fully understood. This study investigated the role of airborne endotoxin on the initiation of antigen-specific airway allergic responses.
  
  
  METHODS
  ELISA methods for detection of isotypes of antigen-specific antibodies and competitive reverse transcription polymerase chain reaction for detection mRNA of cytokines were used. In addition, Liu stain method was used to analyse the amounts of eosinophils in bronchoalveolar lavage fluid.
  
  
  RESULTS
  Mice pre-exposed with airborne endotoxin mounted significantly higher amounts of OVA-specific IgE antibody responses to inhaled OVA than those OVA-only sensitized mice. Inhaled endotoxin could downregulate repeated airway antigen exposure-induced IgE isotype-specific tolerance and increase antigen-induced lung eosinophils infiltration.
  
  
  CONCLUSIONS
  These data show that airborne endotoxin exposure could potentiate allergen-specific airway inflammation. The results should have potential implications for understanding the development of allergen-induced airway allergic responses.
authors.affiliation: Graduate Institute of Environmental Health, College of Public Health, National Taiwan University, Taipei, Taiwan.
authors.forename: G H
authors.initials: GH
authors.lastname: Wan
authors.forename: C S
authors.initials: CS
authors.lastname: Li
authors.forename: R H
authors.initials: RH
authors.lastname: Lin
mesh_terms: D000336:Aerosols; D000485:Allergens / Q000009:adverse effects*; D000818:Animals; D001249:Asthma / Q000209:etiology* / Q000235:genetics / Q000276:immunology; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D004804:Eosinophils / Q000276:immunology; D004926:Escherichia coli; D005260:Female; D007073:Immunoglobulin E / Q000032:analysis; D007074:Immunoglobulin G / Q000032:analysis; D007958:Leukocyte Count; D008070:Lipopolysaccharides / Q000008:administration & dosage*; D008168:Lung / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D010047:Ovalbumin / Q000276:immunology*; D012333:RNA, Messenger / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D000336:Aerosols; D000485:Allergens; D016207:Cytokines; D007074:Immunoglobulin G; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D007073:Immunoglobulin E; D010047:Ovalbumin