title: ER-MP12 antigen, a new cell surface marker on mouse bone marrow cells with thymus-repopulating ability: II. Thymus-homing ability and phenotypic characterization of ER-MP12-positive bone marrow cells.
abstract: In the accompanying paper we showed that six distinct subsets of bone marrow (BM) cells can be identified using the mAb ER-MP12 and ER-MP20 in two-colour immunofluorescence analysis. Upon intrathymic transfer into sublethally irradiated mice thymus-repopulating ability was restricted to ER-MP20- BM cells expressing either high or intermediate levels of the ER-MP12 antigen (1-2% and approximately 30% of BM nucleated cells respectively). The highest frequency of thymus-repopulating cells was found in the minor subset of ER-MP12(+)+20- BM cells. In the present study we demonstrate that upon intravenous transfer, thymus-homing and -repopulating BM cells are exclusively confined to the ER-MP12(+)+20- and ER-MP12+20- subpopulations, the highest frequency being detected among ER-MP12(+)+20- BM cells. Analysis of the peripheral blood leucocytes of reconstituted mice showed that not only prothymocytes but also progenitor cells of the B cell lineage as well as the myeloid lineage were present within both subsets. Three-colour flow cytometric analysis revealed that ER-MP12(+)+20- BM cells in particular were phenotypically heterogeneous with respect to the expression of the cell surface markers Thy-1, Sca-1, CD44, B220 and c-kit. Taken together our data demonstrate that ER-MP12 positively identifies BM cells with the ability to home to and repopulate the thymus. The phenotypic heterogeneity displayed by the ER-MP12(+)+20- BM subset, containing the highest frequency of thymus-homing and -repopulating cells, provides a basis for further separation of prothymocyte activity from other haematopoietic activities in the BM of the mouse.
authors.affiliation: Department of Immunology, Erasmus University, Rotterdam, The Netherlands.
authors.forename: W A
authors.initials: WA
authors.lastname: Slieker
authors.forename: J C
authors.initials: JC
authors.lastname: van der Loo
authors.forename: M F
authors.initials: MF
authors.lastname: de Rijk-de Bruijn
authors.forename: D I
authors.initials: DI
authors.lastname: Godfrey
authors.forename: P J
authors.initials: PJ
authors.lastname: Leenen
authors.forename: W
authors.initials: W
authors.lastname: van Ewijk
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000954:Antigens, Surface / Q000276:immunology*; D015415:Biomarkers; D001853:Bone Marrow / Q000276:immunology*; D001854:Bone Marrow Cells; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000276:immunology; D016130:Immunophenotyping; D016219:Immunotherapy, Adoptive; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D013601:T-Lymphocytes / Q000166:cytology; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D015415:Biomarkers