title: Formalin-fixed Staphylococcus aureus particles prevent allergic sensitization in a murine model of type I allergy.
abstract: BACKGROUND
  Bacterial infections are supposed to act counterregulatory to the development of allergen-specific Th2 immune responses. We analyzed whether administration of extracellular Staphylococcus aureus inhibited experimental sensitization against allergens.
  
  
  METHODS
  BALB/c mice were immunized with alum-adsorbed ovalbumin (OVA) together with formalin-fixed Staphylococcus particles. OVA-specific antibody production and cytokine synthesis by spleen cells was analyzed. Airway reactivity and cellular infiltration into the airways was assessed after intranasal challenge of mice with OVA. In addition, the capacity of Staphylococcus particles to modulate cytokine production by bone marrow-derived dendritic cells was analyzed in vitro.
  
  
  RESULTS
  Simultaneous application of OVA and Staphylococcus particles very efficiently inhibited production of specific IgE and IgG1 as well as secretion of IL-4 and IL-5 by splenocytes, while enhancing IgG2a formation and production of IFN-gamma, indicating a shift from a Th2 response towards a Th1-biased response. This effect was not dependent on the expression of protein A by Staphylococcus. An enhanced frequency or activity of regulatory T cells after administration of Staphylococcus particles was not apparent. Treatment of mice with Staphylococcus particles during the sensitization phase prevented lung inflammation (airway hyperreactivity, eosinophilia) after local challenge with OVA. Culture of bone marrow-derived dendritic cells with Staphylococcus particles induced IL-12p35 and p40 mRNA expression as well as secretion of IL-12p70, and increased production of IL-10 mRNA and protein.
  
  
  CONCLUSIONS
  Administration of formalin-fixed Staphylococcus particles induced Th1-biased immune responses and prevented allergic sensitization.
authors.affiliation: Clinical Research Unit Allergology, Department of Dermatology, Johannes Gutenberg University, Mainz, Germany.
authors.forename: Karina
authors.initials: K
authors.lastname: Gisch
authors.forename: Nadine
authors.initials: N
authors.lastname: Gehrke
authors.forename: Matthias
authors.initials: M
authors.lastname: Bros
authors.forename: Christina
authors.initials: C
authors.lastname: Priesmeyer
authors.forename: Jurgen
authors.initials: J
authors.lastname: Knop
authors.forename: Angelika B
authors.initials: AB
authors.lastname: Reske-Kunz
authors.forename: Stephan
authors.initials: S
authors.lastname: Sudowe
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004195:Disease Models, Animal; D005260:Female; D005404:Fixatives; D005557:Formaldehyde; D006967:Hypersensitivity / Q000145:classification / Q000276:immunology / Q000517:prevention & control*; D007114:Immunization; D051379:Mice; D008807:Mice, Inbred BALB C; D052638:Particulate Matter / Q000276:immunology; D013211:Staphylococcus aureus / Q000276:immunology*
chemical_list: D005404:Fixatives; D052638:Particulate Matter; D005557:Formaldehyde