title: Virus-induced eosinophil mediator release requires antigen-presenting and CD4+ T cells.
abstract: BACKGROUND
  The most frequent trigger of asthma exacerbation is infection with common airway viruses; however, the precise mechanism regulating such severe reactions is not understood. The presence of airway eosinophil products is a unique feature detected in asthmatic airways. Using an animal model, we previously demonstrated that T cells play an important role in regulating an eosinophil-dependant pathway of virus-induced airway hyperreactivity. We hypothesize that human eosinophils respond to viruses, although only after interaction with T cells.
  
  
  OBJECTIVE
  We sought to determine whether eosinophils can respond to airway viruses in vitro and determine the mechanism of response.
  
  
  METHODS
  An in vitro coculture model of human eosinophils, antigen-presenting cells, and T cells was used with parainfluenza virus, respiratory syncytial virus, or rhinovirus. We measured release of eosinophil peroxidase (EPO) in concert with T-cell proliferation, cytokine release, and changes in T-cell phenotype.
  
  
  RESULTS
  The viruses induced release of EPO when coincubated in the presence of antigen-presenting cells (dendritic cells or macrophages) and T cells. Virus-mediated release was associated with proliferation of CD3(+)CD4(+) T cells and release of cytokines. UV inactivation of the virus did not prevent virus-induced EPO release or T-cell proliferation. Proliferating CD4(+) T cells show increased expression of CD25 and CD45RO. CD8(+) T cells were not activated.
  
  
  CONCLUSIONS
  Virus-induced EPO release can occur in the context of antigen presentation to CD4(+) T cells.
authors.affiliation: Pulmonary Research Group, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Francis
authors.initials: F
authors.lastname: Davoine
authors.forename: Min
authors.initials: M
authors.lastname: Cao
authors.forename: Yingqi
authors.initials: Y
authors.lastname: Wu
authors.forename: Farnam
authors.initials: F
authors.lastname: Ajamian
authors.forename: Ramses
authors.initials: R
authors.lastname: Ilarraza
authors.forename: Andy I
authors.initials: AI
authors.lastname: Kokaji
authors.forename: Redwan
authors.initials: R
authors.lastname: Moqbel
authors.forename: Darryl J
authors.initials: DJ
authors.lastname: Adamko
mesh_terms: D017951:Antigen Presentation; D000938:Antigen-Presenting Cells / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D049109:Cell Proliferation; D002478:Cells, Cultured; D018920:Coculture Techniques; D016207:Cytokines / Q000096:biosynthesis / Q000276:immunology; D047209:Eosinophil Peroxidase / Q000378:metabolism*; D004804:Eosinophils / Q000276:immunology*; D006801:Humans; D010222:Parainfluenza Virus 1, Human / Q000276:immunology; D018113:Respiratory Syncytial Virus, Human / Q000276:immunology; D012229:Rhinovirus / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D013601:T-Lymphocytes; D014780:Viruses / Q000276:immunology* / Q000378:metabolism
chemical_list: D016207:Cytokines; D047209:Eosinophil Peroxidase