title: Costimulation by B7 modulates specificity of cytotoxic T lymphocytes: a missing link that explains some bystander T cell activation.
abstract: It has been proposed that some bystander T cell activation may in fact be due to T cell antigen receptor (TCR) cross-reactivity that is too low to be detected by the effector cytotoxic T lymphocyte (CTL). However, this hypothesis is not supported by direct evidence since no TCR ligand is known to induce T cell proliferation and differentiation without being recognized by the effector CTL. Here we report that transgenic T cells expressing a T cell receptor to influenza virus A/NT/68 nucleoprotein (NP) 366-374:Db complexes clonally expand and become effector CTLs in response to homologous peptides from either A/PR8/34 (H1N1), A/AA/60 (H2N2), or A/NT/68 (H3N2). However, the effector T cells induced by each of the three peptides kill target cells pulsed with NP peptides from the H3N2 and H2N2 viruses, but not from the H1N1 virus. Thus, NP366-374 from influenza virus H1N1 is the first TCR ligand that can induce T cell proliferation and differentiation without being recognized by CTLs. Since induction of T cell proliferation was mediated by antigen-presenting cells that express costimulatory molecules such as B7, we investigated if cytolysis of H1N1 NP peptide-pulsed targets can be restored by expressing B7-1 on the target cells. Our results revealed that this is the case. These data demonstrated that costimulatory molecule B7 modulates antigen specificity of CTLs, and provides a missing link that explains some of the bystander T cell activation.
authors.affiliation: Michael Heidelberger Division of Immunology, Department of Pathology, New York University Medical Center 10016, USA.
authors.forename: P
authors.initials: P
authors.lastname: Zheng
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000818:Animals; D000956:Antigens, Viral / Q000276:immunology; D018122:B7-1 Antigen / Q000276:immunology*; D009980:Influenza A virus / Q000276:immunology; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009698:Nucleoproteins / Q000276:immunology; D010446:Peptide Fragments / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000378:metabolism; D014758:Viral Core Proteins / Q000276:immunology
chemical_list: D000956:Antigens, Viral; D018122:B7-1 Antigen; D009698:Nucleoproteins; D010446:Peptide Fragments; D011948:Receptors, Antigen, T-Cell; D014758:Viral Core Proteins; C102366:nucleoprotein (366-374), influenza virus