title: TNF receptor type 2 (p75) functions as a costimulator for antigen-driven T cell responses in vivo.
abstract: Naive T cells require costimulation for robust Ag-driven differentiation and survival. Members of the TNFR family have been shown to provide costimulatory signals conferring survival at distinct phases of the T cell response. In this study, we show that CD4 and CD8 T cells depend on TNFR type 2 (p75) for survival during clonal expansion, allowing larger accumulation of effector cells and conferring protection from apoptosis for a robust memory pool in vivo. We demonstrate using the MHC class I-restricted 2C TCR and MHC class II-restricted AND TCR transgenic systems that TNFR2 regulates the threshold for clonal expansion of CD4 and CD8 T cell subsets in response to cognate Ag. Using a novel recombinant Listeria monocytogenes (rLM) expressing a secreted form of the 2C agonist peptide (SIY) to investigate the role of TNFR2 for T cell immunity in vivo, we found that TNFR2 controls the survival and accumulation of effector cells during the primary response. TNFR2-/- CD8 T cells exhibit loss of protection from apoptosis that is correlated with diminished survivin and Bcl-2 expression. Null mutant mice were more susceptible to rLM-SIY challenge at high doses of primary infection, correlating with impaired LM-specific T cell response in the absence of TNFR2-mediated costimulation. Moreover, the resulting memory pools specific for SIY and listeriolysin O epitopes derived from rLM-SIY were diminished in TNFR2-/- mice. Thus, examination of Ag-driven T cell responses revealed a hitherto unknown costimulatory function for TNFR2 in regulating T cell survival during the differentiation program elicited by intracellular pathogen in vivo.
authors.affiliation: Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Edward Y
authors.initials: EY
authors.lastname: Kim
authors.forename: John J
authors.initials: JJ
authors.lastname: Priatel
authors.forename: Soo-Jeet
authors.initials: SJ
authors.lastname: Teh
authors.forename: Hung-Sia
authors.initials: HS
authors.lastname: Teh
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000008:administration & dosage; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology; D002454:Cell Differentiation; D002470:Cell Survival; D008089:Listeria monocytogenes / Q000276:immunology; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D047889:Receptors, Tumor Necrosis Factor, Type II / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*
chemical_list: D000942:Antigens, Bacterial; D047889:Receptors, Tumor Necrosis Factor, Type II