title: Loading of MHC class I and II presentation pathways by exogenous antigens: a quantitative in vivo comparison.
abstract: The MHC class I pathway is usually fueled by endogenous Ags, while exogenous Ags reach the MHC class II pathway. Although exogenous epitopes may also enter the MHC class I pathway, quantification of the efficiency of the process has remained a difficult task. In an attempt of such a quantification, we directly compared the amount of exogenous virus-like particles required for induction of cytotoxic T cell responses by cross-priming with the amount of virus-like particles required for induction of Th cell responses by the conventional route of MHC class II loading as an internal standard. Surprisingly, we found that cross-presentation of peptides derived from exogenous Ags on MHC class I molecules is of only marginally lower efficiency ( approximately 1- to 10-fold) than the classical MHC class II pathway in vitro and in vivo. Thus, Ag quantities required for cross-presentation and cross-priming are similar to those required for fueling the MHC class II pathway.
authors.affiliation: Cytos Biotechnology, AG, Zürich, Switzerland.
authors.forename: Tazio
authors.initials: T
authors.lastname: Storni
authors.forename: Martin F
authors.initials: MF
authors.lastname: Bachmann
mesh_terms: D000818:Animals; D017951:Antigen Presentation / Q000235:genetics / Q000276:immunology*; D000956:Antigens, Viral / Q000008:administration & dosage* / Q000235:genetics / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism / Q000821:virology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism / Q000821:virology; D004306:Dose-Response Relationship, Immunologic; D006023:Glycoproteins / Q000008:administration & dosage* / Q000235:genetics / Q000276:immunology*; D006183:H-2 Antigens / Q000276:immunology / Q000378:metabolism*; D006512:Hepatitis B Core Antigens / Q000008:administration & dosage* / Q000235:genetics / Q000276:immunology*; D064532:Histocompatibility Antigen H-2D; D000949:Histocompatibility Antigens Class II / Q000276:immunology / Q000378:metabolism*; D007275:Injections, Intravenous; D008213:Lymphocyte Activation / Q000276:immunology; D018655:Lymphocyte Count; D008217:Lymphocytic choriomeningitis virus / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D010446:Peptide Fragments / Q000008:administration & dosage* / Q000235:genetics / Q000276:immunology*; D011485:Protein Binding / Q000235:genetics / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000276:immunology / Q000378:metabolism; D014764:Viral Proteins / Q000008:administration & dosage* / Q000235:genetics / Q000276:immunology*; D014771:Virion / Q000235:genetics / Q000276:immunology
chemical_list: D000956:Antigens, Viral; D006023:Glycoproteins; D006183:H-2 Antigens; D006512:Hepatitis B Core Antigens; D064532:Histocompatibility Antigen H-2D; D000949:Histocompatibility Antigens Class II; C474482:I-A(b) antigen, mouse; D010446:Peptide Fragments; D011948:Receptors, Antigen, T-Cell; D011994:Recombinant Proteins; D014764:Viral Proteins; C094244:glycoprotein peptide 33-41, Lymphocytic choriomeningitis virus