title: Lineage choices in the developing thymus: choosing the T and NKT pathways.
abstract: Thymic development proceeds through several defined stages that generate not only alpha beta and gamma delta T cells but can produce dendritic cells and B cells. The earliest thymocytes exist in the CD4(-)CD8(-) double negative compartment within a heterogeneous fraction termed DN1. Recent progress has identified several candidate populations that may be the bone fide T-cell progenitor population. The potential roles of these populations, which include hematopoietic stem cells, early lymphocyte precursors, common lymphoid progenitors, and early T lineage progenitors are being elucidated. The alpha beta T-cell lineage consists of distinct subsets, one of which is NKT cells. The developmental relationship of NKT cells to conventional T cells has been controversial. Recent work has shown that these cells are probably derived from CD4(+)CD8(+) thymocytes. The discovery and application of CD1d tetramers has made it possible to more fully describe NKT-cell development.
authors.affiliation: Department of Pathology and Laboratory Medicine, Abramson Family Cancer Research Institute, Institute for Medicine and Engineering, University of Pennsylvania, 611 BRB II/III, 421 Curie Boulevard, Philadelphia, PA 19104-6160, USA. wpear@mail.med.upenn.edu
authors.forename: Warren S
authors.initials: WS
authors.lastname: Pear
authors.forename: LiLi
authors.initials: L
authors.lastname: Tu
authors.forename: Paul L
authors.initials: PL
authors.lastname: Stein
mesh_terms: D000818:Animals; D001853:Bone Marrow / Q000276:immunology; D019070:Cell Lineage; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000276:immunology; D007694:Killer Cells, Natural / Q000378:metabolism* / Q000502:physiology; D051379:Mice; D008954:Models, Biological; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology*