title: Essential role of dendritic cell CD80/CD86 costimulation in the induction, but not reactivation, of TH2 effector responses in a mouse model of asthma.
abstract: BACKGROUND
  Airway dendritic cells (DCs) are crucial for the generation of TH2 cells from naive T cells during sensitization and for reactivation of primed TH2 cells on allergen challenge in mouse models of asthma. It is unknown whether CD80/CD86 costimulation is necessary during both phases of the response because primed T cells rely less on costimulatory molecules compared with naive T cells.
  
  
  OBJECTIVE
  We sought to study the contribution of CD80/CD86 costimulatory molecules on DCs during sensitization or challenge in a mouse model of asthma.
  
  
  METHODS
  Naive BALB/c mice received an intratracheal injection of ovalbumin (OVA)-pulsed DCs obtained from the bone marrow of wild-type (WT) or CD80/CD86-/- mice and were subsequently challenged with OVA aerosol to address the role of costimulation during sensitization. OVA-sensitized mice received OVA-pulsed WT or CD80/CD86-/- DCs without OVA aerosol to address the role of costimulation during challenge.
  
  
  RESULTS
  WT DCs induced the proliferation and effector TH2 differentiation of naive OVA-specific T cells, whereas CD80/CD86-/- DCs induced only proliferation. Not surprisingly, WT DCs but not CD80/CD86-/- DCs induced sensitization to OVA in naive mice. In contrast, in OVA-sensitized mice intratracheal injection of CD80/CD86-/- OVA-pulsed DCs led to eosinophilic airway inflammation, goblet cell hyperplasia, and effector TH2 cytokine production that was not different from that seen after injection with WT OVA-DCs, even when the inducible costimulator ICOS was blocked or cytotoxic T lymphocyte-associated antigen 4 immunoglobulin was given.
  
  
  CONCLUSIONS
  CD80/CD86 costimulation on DCs is only necessary during priming of naive T cells into TH2 cells but not during restimulation of previously primed TH2 cells in the challenge phase.
authors.affiliation: Department of Pulmonary and Critical Care Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands. L.vanrijt@erasmusmc.nl
authors.forename: Leonie S
authors.initials: LS
authors.lastname: van Rijt
authors.forename: Nanda
authors.initials: N
authors.lastname: Vos
authors.forename: Monique
authors.initials: M
authors.lastname: Willart
authors.forename: Alex
authors.initials: A
authors.lastname: Kleinjan
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Coyle
authors.forename: Henk C
authors.initials: HC
authors.lastname: Hoogsteden
authors.forename: Bart N
authors.initials: BN
authors.lastname: Lambrecht
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000276:immunology*; D001249:Asthma / Q000276:immunology*; D018122:B7-1 Antigen / Q000276:immunology*; D051940:B7-2 Antigen; D003713:Dendritic Cells / Q000276:immunology*; D005260:Female; D008168:Lung; D008213:Lymphocyte Activation / Q000276:immunology; D008562:Membrane Glycoproteins / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D023421:Models, Animal; D018418:Th2 Cells / Q000276:immunology*
chemical_list: D015703:Antigens, CD; D018122:B7-1 Antigen; D051940:B7-2 Antigen; C497965:Cd86 protein, mouse; D008562:Membrane Glycoproteins