title: Cutting edge: Secondary lymphoid organs are essential for maintaining the CD4, but not CD8, naive T cell pool.
abstract: Despite declining thymic output with age, the peripheral naive T cell pool of an adult animal remains remarkably stable. Therefore, a central question in immunology is how the naive T cell pool is maintained. Here we show that the maintenance of the naive CD4, but not CD8, T cell population in the thymectomized adult mouse is dependent on the presence of secondary lymphoid tissues. This finding is explained by the inability of naive CD4 T cells to sustain normal levels of the survival molecule Bcl-2 or to undergo homeostatic proliferation in the absence of secondary lymphoid organs. Thus, naive CD4 T cells must traffic through secondary lymphoid organs to maintain a stable CD4 pool while naive CD8 T cells encounter their survival and proliferation signals outside the organized structures of secondary lymphoid tissues.
authors.affiliation: Sections of Nephrology and Immunobiology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520, USA. zhenhua.dai@yale.edu
authors.forename: Z
authors.initials: Z
authors.lastname: Dai
authors.forename: F G
authors.initials: FG
authors.lastname: Lakkis
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002478:Cells, Cultured; D006706:Homeostasis; D018960:Hyaluronan Receptors / Q000032:analysis; D016130:Immunophenotyping; D008198:Lymph Nodes / Q000276:immunology; D008213:Lymphocyte Activation; D018655:Lymphocyte Count; D008221:Lymphoid Tissue / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D010581:Peyer's Patches / Q000276:immunology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D013154:Spleen / Q000276:immunology; D013156:Splenectomy; D016176:T-Lymphocyte Subsets / Q000145:classification; D013934:Thymectomy
chemical_list: D018960:Hyaluronan Receptors; D019253:Proto-Oncogene Proteins c-bcl-2