title: Modified Th2 responses at high-dose exposures to allergen: using an occupational model.
abstract: BACKGROUND
  The relationships between allergen exposures and allergy and asthma are complex. High exposure levels to cat allergen are associated with IgG- and IgG(4)-specific antibody responses without sensitization or risk of asthma, a process described as a "modified Th2 response." Attenuation of risk of allergy and asthma at high exposure levels has been reported in longitudinal studies of both childhood and occupational asthma.
  
  
  OBJECTIVE
  To investigate, using an occupational model, the relationships among estimated exposure to aeroallergens, the production of specific IgE, IgG and IgG(4) antibodies, and the prevalence of associated symptoms.
  
  
  METHODS
  Cross-sectional survey of employees exposed to rats at work on six pharmaceutical sites across the United Kingdom. A total of 689 (89%) provided a blood sample and completed a questionnaire.
  
  
  RESULTS
  At highest exposure to rats, there was an attenuation of the exposure response for sensitization and symptoms. In contrast, the frequency of individuals producing high quantities of specific IgG and IgG(4) increased with exposure intensity. Ratios of IgG(4)/IgE were highest in those handling the greatest number of rats. Risk of developing work-related chest symptoms was lower for those who produced both specific IgE and IgG(4) compared to those with specific IgE only.
  
  
  CONCLUSIONS
  High exposure to rats is associated with lower rates of specific IgE and symptoms but an increased frequency of high specific IgG and IgG(4) production. Specific IgG(4) produced together with specific IgE may reduce the risk of developing work-related chest symptoms compared with when specific IgE is produced alone.
authors.affiliation: Department of Occupational and Environmental Medicine, Faculty of Medicine, Imperial College (NHLI), London, United Kingdom.
authors.forename: Hayley
authors.initials: H
authors.lastname: Jeal
authors.forename: Adrian
authors.initials: A
authors.lastname: Draper
authors.forename: Jessica
authors.initials: J
authors.lastname: Harris
authors.forename: Anthony Newman
authors.initials: AN
authors.lastname: Taylor
authors.forename: Paul
authors.initials: P
authors.lastname: Cullinan
authors.forename: Meinir
authors.initials: M
authors.lastname: Jones
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000485:Allergens / Q000276:immunology*; D000818:Animals; D001249:Asthma / Q000097:blood* / Q000276:immunology; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood*; D007074:Immunoglobulin G / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000097:blood* / Q000276:immunology; D016273:Occupational Exposure; D051381:Rats / Q000276:immunology*; D018418:Th2 Cells / Q000502:physiology
chemical_list: D000485:Allergens; D007074:Immunoglobulin G; D007073:Immunoglobulin E