title: Early T-cell progenitors are the major granulocyte precursors in the adult mouse thymus.
abstract: The mouse thymus supports T-cell development, but also contains non-T-cell lineages such as dendritic cells, macrophages, and granulocytes that are necessary for T-cell repertoire selection and apoptotic thymocyte clearance. Early thymic progenitors (ETPs) are not committed to the T-cell lineage, as demonstrated by both in vitro and in vivo assays. Whether ETPs realize non-T-cell lineage potentials in vivo is not well understood and indeed is controversial. In the present study, we investigated whether ETPs are the major precursors of any non-T-lineage cells in the thymus. We analyzed the development of these populations under experimental circumstances in which ETPs are nearly absent due to either abrogated thymic settling or inhibition of early thymic development by genetic ablation of IL-7 receptorα or Hes1. Results obtained using multiple in vivo approaches indicate that the majority of thymic granulocytes derive from ETPs. These data indicate that myelolymphoid progenitors settle the thymus and thus clarify the pathways by which stem cells give rise to downstream blood cell lineages.
authors.affiliation: Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Maria Elena
authors.initials: ME
authors.lastname: De Obaldia
authors.forename: J Jeremiah
authors.initials: JJ
authors.lastname: Bell
authors.forename: Avinash
authors.initials: A
authors.lastname: Bhandoola
mesh_terms: D000818:Animals; D020296:Animals, Congenic; D051792:Basic Helix-Loop-Helix Proteins / Q000172:deficiency / Q000502:physiology*; D016026:Bone Marrow Transplantation; D019070:Cell Lineage; D002465:Cell Movement; D005260:Female; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D006098:Granulocytes / Q000166:cytology*; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D018398:Homeodomain Proteins / Q000096:biosynthesis / Q000502:physiology*; D038041:Lymphopoiesis / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D011828:Radiation Chimera; D020395:Receptors, Interleukin-7 / Q000172:deficiency / Q000502:physiology*; D016176:T-Lymphocyte Subsets / Q000166:cytology*; D013950:Thymus Gland / Q000166:cytology* / Q000254:growth & development; D000072056:Transcription Factor HES-1
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D018398:Homeodomain Proteins; D020395:Receptors, Interleukin-7; D000072056:Transcription Factor HES-1; C489734:Hes1 protein, mouse; C415350:interleukin-7 receptor, alpha chain; C064658:RAG-1 protein