title: Transferrin receptor mediates uptake and presentation of hepatitis B envelope antigen by T lymphocytes.
abstract: Human activated T lymphocytes expressing class II molecules are able to present only complex antigens that bind to their own surface receptors, and thus can be captured, internalized, and processed through the class II major histocompatibility complex processing pathway. We have used the antigen-presenting T cell system to identify the viral receptor used by hepatitis B virus (HBV) to enter cells, as well as the sequence of HB envelope antigen (HBenvAg) involved in this interaction. Results show that both CD4+ and CD8+ T clones can process and present HBenvAg to class II-restricted cytotoxic T lymphocytes and that the CD71 transferrin receptor (TfR) is involved in efficient HBenvAg uptake by T cells. Moreover, we provide evidence that the HBenvAg sequence interacting with the T cell surface is contained within the pre-S2 region. Since TfR is also expressed on hepatocytes, it might represent a portal of cellular entry for HBV infection. This system of antigen presentation by T cells may serve as a model to study both lymphocyte receptors used by lymphocytotropic viruses and viral proteins critical to bind them.
authors.affiliation: Immunology Unit, Universitá La Sapienza, Rome, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Franco
authors.forename: M
authors.initials: M
authors.lastname: Paroli
authors.forename: U
authors.initials: U
authors.lastname: Testa
authors.forename: R
authors.initials: R
authors.lastname: Benvenuto
authors.forename: C
authors.initials: C
authors.lastname: Peschle
authors.forename: F
authors.initials: F
authors.lastname: Balsano
authors.forename: V
authors.initials: V
authors.lastname: Barnaba
mesh_terms: D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology; D000938:Antigen-Presenting Cells / Q000276:immunology / Q000378:metabolism*; D015704:CD4 Antigens; D016827:CD8 Antigens; D006514:Hepatitis B Surface Antigens / Q000276:immunology / Q000378:metabolism*; D008969:Molecular Sequence Data; D011498:Protein Precursors / Q000276:immunology / Q000378:metabolism; D011990:Receptors, Transferrin / Q000378:metabolism*; D012995:Solubility; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D014168:Transferrin / Q000037:antagonists & inhibitors / Q000378:metabolism; D014759:Viral Envelope Proteins / Q000276:immunology / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; D015704:CD4 Antigens; D016827:CD8 Antigens; D006514:Hepatitis B Surface Antigens; D011498:Protein Precursors; D011990:Receptors, Transferrin; D014168:Transferrin; D014759:Viral Envelope Proteins; C050807:presurface protein 2, hepatitis B surface antigen