title: Different effects of endotoxin versus mite and cat allergen exposure on T-cell differentiation in infants.
abstract: BACKGROUND
  Early exposure to bacterial endotoxin has been proposed to protect against allergy development in children. Whether endotoxin is able to direct T-cell differentiation into a predominance of type 1 immunity is still unresolved.
  
  
  OBJECTIVE
  We sought to compare the effects of endotoxin and mite and cat allergens on T-cell differentiation in infants.
  
  
  METHODS
  In a random population sample of 135 2-year-old children of an ongoing birth-cohort study, peripheral blood CD4+ and CD8+ T-cell subsets were defined by the expression of the chemokine receptors CCR5 and CCR3 as surrogate markers for type 1 and type 2 T cells, respectively. Endotoxin and mite and cat allergens were measured in house dust collected from the mother's mattress at the child's age of 3 months to assess early exposure.
  
  
  RESULTS
  In the CD4+ T-cell subset, endotoxin levels were positively associated with high proportions of type 1 CCR5+ cells (odds ratio for fourth exposure quartile [OR(Q4)], 7.68; 95% CI, 1.35-43.75), whereas cat allergen levels were associated with increased proportions of type 2 CCR3+ cells (OR(Q4), 4.07; 95% CI, 1.05-15.85). In contrast to endotoxin, allergen levels were associated with CD8+ T cells, showing an inverse relationship between mite allergen concentrations and high proportions of CCR5+ or CCR3+ cells (CCR5+ cells: OR(Q4), 0.14; 95% CI, 0.03-0.74; CCR3+ cells: OR(Q4), 0.16; 95% CI, 0.03-0.89) and a positive association of cat allergen levels with increased proportions of CCR5+ cells (OR(Q4), 9.24, 95% CI, 1.61-53.10), as well as CCR3+ cells (OR(Q3), 6.64; 95% CI, 1.21-36.51).
  
  
  CONCLUSIONS
  Our results indicate that endotoxin has the potential to promote the development of type 1 CD4+ T cells, whereas mite and cat allergens primarily modify the proportion of CD8+ cells of both types.
authors.affiliation: GSF National Research Center for Environment and Health, Institute of Epidemiology, Ingolstaedter-Landstrasse 1, D-85764 Neuherberg, Germany.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Bolte
authors.forename: Susanne
authors.initials: S
authors.lastname: Krauss-Etschmann
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Konstantopoulos
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Bischof
authors.forename: Bärbel
authors.initials: B
authors.lastname: Fahlbusch
authors.forename: Dolores J
authors.initials: DJ
authors.lastname: Schendel
authors.forename: H Erich
authors.initials: HE
authors.lastname: Wichmann
authors.forename: Joachim
authors.initials: J
authors.lastname: Heinrich
mesh_terms: D000485:Allergens / Q000494:pharmacology*; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000378:metabolism; D002415:Cats / Q000276:immunology*; D002454:Cell Differentiation / Q000187:drug effects; D015331:Cohort Studies; D004731:Endotoxins / Q000494:pharmacology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008925:Mites / Q000276:immunology*; D054397:Receptors, CCR3; D019713:Receptors, CCR5 / Q000378:metabolism; D019707:Receptors, Chemokine / Q000378:metabolism; D013601:T-Lymphocytes / Q000166:cytology* / Q000378:metabolism
chemical_list: D000485:Allergens; C515350:CCR3 protein, human; D004731:Endotoxins; D054397:Receptors, CCR3; D019713:Receptors, CCR5; D019707:Receptors, Chemokine