title: Peptide variants of viral CTL epitopes mediate positive selection and emigration of Ag-specific thymocytes in vivo.
abstract: During development, thymocytes carrying TCRs mediating low-affinity interactions with MHC-bound self-peptides are positively selected for export into the mature peripheral T lymphocyte pool. Thus, exogenous administration of certain altered peptide ligands (APL) with reduced TCR affinity relative to cognate Ags may provide a tool to elicit maturation of desired TCR specificities. To test this "thymic vaccination" concept, we designed APL of the viral CTL epitopes gp33-41 and vesicular stomatitis virus nucleoprotein octapeptide N52-59 relevant for the lymphocytic choriomeningitis virus-specific P14- and vesicular stomatitis virus-specific N15-TCRs, respectively, and examined their effects on thymocytes in vivo using irradiation chimeras. Injection of APL into irradiated congenic (Ly-5.1) mice, reconstituted with T cell progenitors from the bone marrow of P14 RAG2(-/-) (Ly-5.2) or N15 RAG2(-/-) (Ly-5.2) transgenic mice, resulted in positive selection of T cells expressing the relevant specificity. Moreover, the variants led to export of virus-specific T cells to lymph nodes, but without inducing T cell proliferation. These findings show that the mature T cell repertoire can be altered by in vivo peptide administration through manipulation of thymic selection.
authors.affiliation: Laboratory of Immunobiology, Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA.
authors.forename: Masha
authors.initials: M
authors.lastname: Fridkis-Hareli
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Reche
authors.forename: Ellis L
authors.initials: EL
authors.lastname: Reinherz
mesh_terms: D000818:Animals; D000941:Antigens / Q000235:genetics / Q000276:immunology; D000956:Antigens, Viral / Q000235:genetics / Q000276:immunology; D017637:Clonal Deletion / Q000276:immunology; D006023:Glycoproteins / Q000235:genetics / Q000276:immunology; D051379:Mice; D010446:Peptide Fragments / Q000235:genetics / Q000276:immunology; D010455:Peptides / Q000235:genetics / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D013950:Thymus Gland / Q000276:immunology*; D014764:Viral Proteins / Q000235:genetics / Q000276:immunology
chemical_list: D000941:Antigens; D000956:Antigens, Viral; D006023:Glycoproteins; D010446:Peptide Fragments; D010455:Peptides; D014764:Viral Proteins; C094244:glycoprotein peptide 33-41, Lymphocytic choriomeningitis virus