title: ER-MP12 antigen, a new cell surface marker on mouse bone marrow cells with thymus-repopulating ability: I. Intrathymic repopulating ability of ER-MP12-positive bone marrow cells.
abstract: We searched for new cell surface markers that allow a positive identification of thymus-repopulating cells in the bone marrow (BM) of the mouse. Recently we raised two rat monoclonal antibodies (ER-MP12 and ER-MP20) that recognize cell surface antigens expressed by mouse haematopoietic progenitor cells, among which are progenitor cells of the macrophage lineage. Here we show that the ER-MP12 antigen, but not the ER-MP20 antigen, is also expressed by BM cells with thymus-repopulating ability. Using ER-MP12 and ER-MP20 in two-colour immunofluorescence analysis six subpopulations of BM cells can be identified. The thymus-repopulating ability of each BM subpopulation was assessed after fluorescence-activated cell sorting and subsequent intrathymic injection into sublethally irradiated Thy-1 congenic recipient mice. Thymus-repopulating activity appeared to be exclusively confined to two subsets of BM cells expressing either high or intermediate levels of the ER-MP12 antigen, but lacking ER-MP20 antigen expression. These BM subsets comprised 1-2% and 30% of total nucleated BM cells respectively. The frequency of thymus-repopulating cells was maximal in the minor BM subpopulation with the highest level of ER-MP12 antigen expression. We conclude that ER-MP12 detects a hitherto unknown cell surface marker expressed by BM cells with thymus-repopulating ability.
authors.affiliation: Department of Immunology, Erasmus University, Rotterdam, The Netherlands.
authors.forename: W A
authors.initials: WA
authors.lastname: Slieker
authors.forename: M F
authors.initials: MF
authors.lastname: de Rijk-de Bruijn
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; D005260:Female; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000276:immunology; D016130:Immunophenotyping; D016219:Immunotherapy, Adoptive; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D051381:Rats; D013601:T-Lymphocytes / Q000166:cytology; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D015415:Biomarkers