title: Flow cytometry imaging identifies rare T(H)2 cells expressing thymic stromal lymphopoietin receptor in a "proallergic" milieu.
abstract: BACKGROUND
  Thymic stromal lymphopoietin (TSLP) is expressed at sites of allergic inflammation, including eczematous skin. This cytokine has been reported to exert its T(H)2-inducing properties through dendritic cells. Expression of TSLP receptor on the surface of activated T(H)2 cells could amplify T(H)2 responses at inflamed sites through the direct actions of TSLP.
  
  
  OBJECTIVE
  To test rigorously whether T(H)2 cells induced by "proallergic" factors express TSLP receptor and characterize these cells using an experimental platform that combines flow cytometry with microscopic capabilities.
  
  
  METHODS
  CD4(+) T cells isolated from patients with atopic dermatitis or normal healthy controls were cocultured with autologous dendritic cells in the presence of T(H)2-promoting stimuli (TSLP ± allergen and staphylococcal enterotoxin B ± TSLP). Surface expression of TSLP receptor was analyzed by image-based flow cytometry, and responsiveness of purified T cells to TSLP was assessed by phosphorylation of signal transducer and activator of transcription-5 and cytokine secretion.
  
  
  RESULTS
  T(H)2-promoting stimuli induced a robust population of activated T(H)2 cells (CD25(+)IL-4(+)). Regardless of the nature of the stimulus, flow cytometry imaging confirmed that T cells expressing TSLP receptor were rare, constituting a minor fraction of the IL-4(+) T cell pool; however, TSLP responsiveness was nonetheless detectable. Analysis of cell size and nuclear morphology revealed preferential expression of TSLP receptor on IL-4-expressing cells undergoing mitosis. Analysis of lesional skin in atopic dermatitis supported the view that rare IL-4(+) T cells expressing TSLP receptor are present at inflamed sites.
  
  
  CONCLUSIONS
  In a "proallergic" milieu, TSLP receptor is preferentially expressed on rare actively dividing T(H)2 cells. The direct action of TSLP on T cells could amplify T(H)2 responses at sites of allergic inflammation.
authors.affiliation: Asthma and Allergic Diseases Center, University of Virginia Health System, Charlottesville, VA 22908-1355, USA.
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Reefer
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: Hulse
authors.forename: Josephine A
authors.initials: JA
authors.lastname: Lannigan
authors.forename: Michael D
authors.initials: MD
authors.lastname: Solga
authors.forename: Paul W
authors.initials: PW
authors.lastname: Wright
authors.forename: Libby A
authors.initials: LA
authors.lastname: Kelly
authors.forename: James
authors.initials: J
authors.lastname: Patrie
authors.forename: Martin D
authors.initials: MD
authors.lastname: Chapman
authors.forename: Judith A
authors.initials: JA
authors.lastname: Woodfolk
mesh_terms: D002469:Cell Separation; D003876:Dermatitis, Atopic / Q000276:immunology* / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology; D018121:Receptors, Cytokine / Q000096:biosynthesis* / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology* / Q000378:metabolism
chemical_list: C498762:CRLF2 protein, human; D018121:Receptors, Cytokine