title: CD4 promotes breadth in the TCR repertoire.
abstract: A diverse population of MHC class II-restricted CD4 lineage T cells develops in mice that lack expression of the CD4 molecule. In this study, we show that the TCR repertoire selected in the absence of CD4 is distinct, but still overlapping in its properties with that selected in the presence of CD4. Immunization of mice lacking CD4 caused the clonal expansion of T cells that showed less breadth in the range of Ag-binding properties exhibited by their TCRs. Specifically, the CD4-deficient Ag-specific TCR repertoire was depleted of TCRs that demonstrated low-affinity binding to their ligands. The data thus suggest a key role for CD4 in broadening the TCR repertoire by potentiating productive TCR signaling and clonal expansion in response to the engagement of low-affinity antigenic ligands.
authors.affiliation: Department of Microbiology and Immunology, University of California, San Francisco, CA 94143, USA.
authors.forename: Q
authors.initials: Q
authors.lastname: Wang
authors.forename: L
authors.initials: L
authors.lastname: Malherbe
authors.forename: D
authors.initials: D
authors.lastname: Zhang
authors.forename: K
authors.initials: K
authors.lastname: Zingler
authors.forename: N
authors.initials: N
authors.lastname: Glaichenhaus
authors.forename: N
authors.initials: N
authors.lastname: Killeen
mesh_terms: D000818:Animals; D000953:Antigens, Protozoan; D015704:CD4 Antigens / Q000235:genetics / Q000276:immunology*; D019070:Cell Lineage; D002999:Clone Cells; D022801:Complementarity Determining Regions / Q000235:genetics; D015329:Gene Rearrangement, T-Lymphocyte; D019674:Genes, T-Cell Receptor beta; D008024:Ligands; D051379:Mice; D008817:Mice, Mutant Strains; D008822:Mice, Transgenic; D015800:Protozoan Proteins / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000953:Antigens, Protozoan; D015704:CD4 Antigens; D022801:Complementarity Determining Regions; D008024:Ligands; D015800:Protozoan Proteins; D011948:Receptors, Antigen, T-Cell; C093139:LACK antigen, Leishmania