title: B cell-derived exosomes can present allergen peptides and activate allergen-specific T cells to proliferate and produce TH2-like cytokines.
abstract: BACKGROUND
  Exosomes are vesicles of 30 to 100 nm produced by inward budding of endosomal compartments and are released by a range of different cell types. Exosomes from antigen-presenting cells carry immunorelevant molecules like MHC class I and II and costimulatory molecules and thus are suggested to have a role in immune modulation.
  
  
  OBJECTIVE
  To investigate the role of antigen-presenting cell derived exosomes in allergen presentation and T-cell stimulation.
  
  
  METHODS
  Exosomes were isolated from supernatants of B-cell lines derived from patients with birch pollen allergy. The exosomes were characterized with regard to the expression of surface molecules by flow cytometry. Moreover, exosomes were loaded with T-cell-activating peptides from the major birch allergen Bet v 1, and binding was tested with ELISA. Loaded exosomes were used for stimulation of Bet v 1-specific T-cell lines. Cell proliferation and cytokine production were assessed.
  
  
  RESULTS
  The exosomes had a phenotype typical of B cell-derived exosomes with expression of MHC, costimulatory molecules like CD86, tetraspanin proteins such as CD81, and CD19. Furthermore, B cell-derived exosomes bound Bet v 1-derived peptides and subsequently induced a dose-dependent T-cell proliferation. In addition to proliferation, T cells synthesized the cytokines IL-5 and IL-13 in response to peptide-loaded exosomes.
  
  
  CONCLUSIONS
  These results demonstrate for the first time that exosomes isolated from B cells can present allergen-derived peptides and thereby induce T-cell proliferation and T(H)2-like cytokine production.
  
  
  CONCLUSIONS
  Our data suggest that exosomes from B lymphocytes are an immunostimulatory factor in allergic immune responses.
authors.affiliation: Department of Medicine, Clinical Allergy Research Unit, Karolinska Institutet, Stockholm, Sweden. Charlotte.Admyre@ki.se
authors.forename: Charlotte
authors.initials: C
authors.lastname: Admyre
authors.forename: Barbara
authors.initials: B
authors.lastname: Bohle
authors.forename: Sara M
authors.initials: SM
authors.lastname: Johansson
authors.forename: Margarete
authors.initials: M
authors.lastname: Focke-Tejkl
authors.forename: Rudolf
authors.initials: R
authors.lastname: Valenta
authors.forename: Annika
authors.initials: A
authors.lastname: Scheynius
authors.forename: Susanne
authors.initials: S
authors.lastname: Gabrielsson
mesh_terms: D000485:Allergens / Q000276:immunology* / Q000378:metabolism; D000938:Antigen-Presenting Cells / Q000276:immunology* / Q000378:metabolism; D052179:Antigens, Plant; D016175:B-Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism; D029662:Betula / Q000276:immunology; D002461:Cell Line, Transformed; D049109:Cell Proliferation; D016207:Cytokines / Q000096:biosynthesis*; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D006801:Humans; D010455:Peptides / Q000276:immunology* / Q000378:metabolism; D011058:Pollen / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D018418:Th2 Cells / Q000276:immunology* / Q000378:metabolism; D022161:Transport Vesicles / Q000276:immunology* / Q000378:metabolism
chemical_list: D000485:Allergens; D052179:Antigens, Plant; D016207:Cytokines; D018984:Epitopes, T-Lymphocyte; D010455:Peptides