title: Characterization of thymic progenitors in adult mouse bone marrow.
abstract: Thymic cellularity is maintained throughout life by progenitor cells originating in the bone marrow. In this study, we describe adult mouse bone cells that exhibit several features characteristic of prothymocytes. These include 1) rapid thymic engraftment kinetics following i.v. transplantation, 2) dramatic expansion of thymic progeny, and 3) limited production of hemopoietic progeny other than thymocytes. The adult mouse bone marrow population that is depleted of cells expressing any of a panel of lineage-specific Ags, stem cell Ag-1 positive, and not expressing the Thy1.1 Ag (Thy1.1(-)) (Thy1.1(-) progenitors) can repopulate the thymus 9 days more rapidly than can hemopoietic stem cells, a rate of thymic repopulation approaching that observed with transplanted thymocytes. Additionally, Thy1.1(-) progenitors expand prolifically to generate thymocyte progeny comparable in absolute numbers to those observed from parallel hemopoietic stem cell transplants, and provide a source of progenitors that spans multiple waves of thymic seeding. Nevertheless, the Thy1.1(-) population yields relatively few B cells and rare myeloid progeny posttransplant. These observations describe the phenotype of an adult mouse bone marrow population highly enriched for rapidly engrafting, long-term thymocyte progenitors. Furthermore, they note disparity in B and T cell expansion from this lymphoid progenitor population and suggest that it contains the progenitor primarily responsible for seeding the thymus throughout life.
authors.affiliation: Department of Pathology, University of Utah, 30 North 1900 East, Salt Lake City, UT 84132, USA.
authors.forename: S Scott
authors.initials: SS
authors.lastname: Perry
authors.forename: L Jeanne
authors.initials: LJ
authors.lastname: Pierce
authors.forename: William B
authors.initials: WB
authors.lastname: Slayton
authors.forename: Gerald J
authors.initials: GJ
authors.lastname: Spangrude
mesh_terms: D000375:Aging / Q000276:immunology; D000818:Animals; D000950:Antigens, Ly / Q000096:biosynthesis; D016175:B-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology; D001854:Bone Marrow Cells / Q000166:cytology* / Q000276:immunology*; D016026:Bone Marrow Transplantation / Q000276:immunology; D002455:Cell Division / Q000276:immunology; D019070:Cell Lineage / Q000276:immunology; D002469:Cell Separation; D002478:Cells, Cultured; D005434:Flow Cytometry; D006085:Graft Survival / Q000276:immunology; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000276:immunology; D007272:Injections, Intralymphatic; D007275:Injections, Intravenous; D008221:Lymphoid Tissue / Q000166:cytology / Q000276:immunology; D008565:Membrane Proteins / Q000096:biosynthesis; D051379:Mice; D020297:Mice, Congenic; D008810:Mice, Inbred C57BL; D019009:Proto-Oncogene Proteins c-kit / Q000096:biosynthesis; D013234:Stem Cells / Q000166:cytology* / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology / Q000637:transplantation; D018800:Thy-1 Antigens / Q000096:biosynthesis; D013950:Thymus Gland / Q000166:cytology* / Q000276:immunology* / Q000637:transplantation
chemical_list: D000950:Antigens, Ly; C074650:Ly6a protein, mouse; D008565:Membrane Proteins; D018800:Thy-1 Antigens; D019009:Proto-Oncogene Proteins c-kit