title: Different levels of T-cell receptor triggering induce distinct functions in hepatitis B and hepatitis C virus-specific human CD4(+) T-cell clones.
abstract: CD4(+) T cells play a major role in the host defense against viruses and intracellular microbes. During the natural course of such an infection, specific CD4(+) T cells are exposed to a wide range of antigen concentrations depending on the body compartment and the stage of disease. While epitope variants trigger only subsets of T-cell effector functions, the response of virus-specific CD4(+) T cells to various concentrations of the wild-type antigen has not been systematically studied. We stimulated hepatitis B virus core- and hepatitis C virus NS3-specific CD4(+) T-cell clones which had been isolated from patients with acute hepatitis during viral clearance with a wide range of specific antigen concentrations and determined the phenotypic changes and the induction of T-cell effector functions in relation to T-cell receptor internalization. A low antigen concentration induced the expression of T-cell activation markers and adhesion molecules in CD4(+) T-cell clones in the absence of cytokine secretion and proliferation. The expression of CD25, HLA-DR, CD69, and intercellular cell adhesion molecule 1 increased as soon as T-cell receptor internalization became detectable. A 30- to 100-fold-higher antigen concentration, corresponding to the internalization of 20 to 30% of T-cell receptor molecules, however, was required for the induction of proliferation as well as for gamma interferon and interleukin-4 secretion. These data indicate that virus-specific CD4(+) T cells can respond to specific antigen in a graded manner depending on the antigen concentration, which may have implications for a coordinate regulation of specific CD4(+) T-cell responses.
authors.affiliation: Institute for Immunology, University of Munich, 80336 Munich, Germany. helmut.diepolder@med2.med.uni-muenchen.de
authors.forename: H M
authors.initials: HM
authors.lastname: Diepolder
authors.forename: N H
authors.initials: NH
authors.lastname: Gruener
authors.forename: J T
authors.initials: JT
authors.lastname: Gerlach
authors.forename: M C
authors.initials: MC
authors.lastname: Jung
authors.forename: E A
authors.initials: EA
authors.lastname: Wierenga
authors.forename: G R
authors.initials: GR
authors.lastname: Pape
mesh_terms: D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002999:Clone Cells; D016174:Hepacivirus / Q000276:immunology*; D006509:Hepatitis B / Q000276:immunology / Q000821:virology; D006512:Hepatitis B Core Antigens / Q000276:immunology; D006515:Hepatitis B virus / Q000276:immunology*; D006526:Hepatitis C / Q000276:immunology / Q000821:virology; D006801:Humans; D007156:Immunologic Memory; D008213:Lymphocyte Activation / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000276:immunology* / Q000378:metabolism*; D015375:Receptors, Interleukin-2 / Q000378:metabolism; D017361:Viral Nonstructural Proteins / Q000276:immunology; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
chemical_list: D015815:Cell Adhesion Molecules; D006512:Hepatitis B Core Antigens; D011948:Receptors, Antigen, T-Cell; D015375:Receptors, Interleukin-2; D017361:Viral Nonstructural Proteins; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases