title: Apoptosis threshold set by Noxa and Mcl-1 after T cell activation regulates competitive selection of high-affinity clones.
abstract: The adaptive immune system generates protective T cell responses via a poorly understood selection mechanism that favors expansion of clones with optimal affinity for antigen. Here we showed that upon T cell activation, the proapoptotic molecule Noxa (encoded by Pmaip1) and its antagonist Mcl-1 were induced. During an acute immune response against influenza or ovalbumin, Pmaip1(-/-) effector T cells displayed decreased antigen affinity and functionality. Molecular analysis of influenza-specific T cells revealed persistence of many subdominant clones in the Pmaip1(-/-) effector pool. When competing for low-affinity antigen, Pmaip1(-/-) TCR transgenic T cells had a survival advantage in vitro, resulting in increased numbers of effector cells in vivo. Mcl-1 protein stability was controlled by T cell receptor (TCR) affinity-dependent interleukin-2 signaling. These results establish a role for apoptosis early during T cell expansion, based on antigen-driven competition and survival of the fittest T cells.
authors.affiliation: Department of Experimental Immunology, Academical Medical Center, 1105 AZ Amsterdam, The Netherlands.
authors.forename: Felix M
authors.initials: FM
authors.lastname: Wensveen
authors.forename: Klaas P J M
authors.initials: KP
authors.lastname: van Gisbergen
authors.forename: Ingrid A M
authors.initials: IA
authors.lastname: Derks
authors.forename: Carmen
authors.initials: C
authors.lastname: Gerlach
authors.forename: Ton N
authors.initials: TN
authors.lastname: Schumacher
authors.forename: René A W
authors.initials: RA
authors.lastname: van Lier
authors.forename: Eric
authors.initials: E
authors.lastname: Eldering
mesh_terms: D056704:Adaptive Immunity; D000818:Animals; D017209:Apoptosis / Q000276:immunology*; D002469:Cell Separation; D002999:Clone Cells; D005434:Flow Cytometry; D015870:Gene Expression; D020869:Gene Expression Profiling; D015151:Immunoblotting; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D008213:Lymphocyte Activation / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000276:immunology*; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: C579094:Mcl1 protein, mouse; D064549:Myeloid Cell Leukemia Sequence 1 Protein; C408009:Pmaip1 protein, mouse; D019253:Proto-Oncogene Proteins c-bcl-2; D011948:Receptors, Antigen, T-Cell