title: Sensitive visualization of peptide presentation in vitro and ex vivo.
abstract: BACKGROUND
  The presentation of antigenic peptides to specific T cells is one of the key events for the induction of a T-cell-dependent immune response. The nature of the antigen-presenting cells which present distinct peptides has been difficult to analyze so far due to the low number of peptides presented in vivo by a single antigen-presenting cell.
  
  
  METHODS
  We have used magnetofluorescent liposomes to identify and characterize antigen-presenting cells according to presentation of a hapten-labeled antigenic peptide in vitro and ex vivo.
  
  
  RESULTS
  Magnetofluorescent liposomes allowed the identification and isolation of antigen-presenting cells according to the presentation of less than 100 peptides per cell, the physiological threshold for activation of specific T cells. Ex vivo, we could demonstrate peptide presentation by B lymphocytes and dendritic cells already 1 h after intravenous peptide injection; this rapidly declined to background level after 12-24 h.
  
  
  CONCLUSIONS
  The sensitive visualization of peptide presentation allows the phenotypical and functional characterization of those antigen-presenting cells which present specific peptides at physiological relevant quantities. This technology will help to characterize the antigen-presenting cells (APC) which are responsible for the induction of distinct immune reactions in vivo, e.g., the generation of tolerance or immunity.
authors.affiliation: Deutsches Rheuma-Forschungszentrum Berlin, Germany.
authors.forename: Désirée
authors.initials: D
authors.lastname: Kunkel
authors.forename: Dennis
authors.initials: D
authors.lastname: Kirchhoff
authors.forename: Rudolf
authors.initials: R
authors.lastname: Volkmer-Engert
authors.forename: Andreas
authors.initials: A
authors.lastname: Radbruch
authors.forename: Alexander
authors.initials: A
authors.lastname: Scheffold
mesh_terms: D000818:Animals; D017951:Antigen Presentation; D000938:Antigen-Presenting Cells / Q000502:physiology; D005260:Female; D005434:Flow Cytometry / Q000379:methods; D006241:Haptens / Q000276:immunology; D066298:In Vitro Techniques; D007275:Injections, Intravenous; D008081:Liposomes / Q000008:administration & dosage / Q000276:immunology; D008280:Magnetics; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008822:Mice, Transgenic; D010455:Peptides / Q000008:administration & dosage / Q000276:immunology* / Q000494:pharmacology; D013047:Specific Pathogen-Free Organisms; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D006241:Haptens; D008081:Liposomes; D010455:Peptides