Expression of Thy-1 on human hematopoietic progenitor cells.
Expression of Thy-1 on hematopoietic cells from human fetal liver (FL), cord blood (CB), and bone marrow (BM) was studied with a novel anti-Thy-1 antibody, 5E10. Specificity of 5E10 for human Thy-1 was demonstrated by immunoprecipitation of a 25-35-kD molecule, and the sequence of a cDNA that was cloned by immunoselection of COS cells transfected with a cDNA library derived from a 5E10+ cell line. Two- and three-color immunofluorescence staining experiments revealed that the Thy-1 expression is restricted to, an average, 1-4% of FL, CB, and BM cells, and binding to these cell types is essentially restricted to a very small subset of lymphoid cells and approximately 25% of CD34+ cells. Thy-1+ CD34+ cells were further characterized as CD38lo/CD45RO+/CD45RA-/CD71lo/c-kit(lo) and rhodamine 123dull. When CD34+ cells were sorted on the basis of Thy-1 expression, the majority of clonogenic cells were recovered in the CD34+Thy-1- fraction, whereas the majority of cells capable of producing myeloid colonies after 5-8 wk of long-term culture (long-term culture initiating cells) were recovered in the Thy-1+CD34+ fraction. In addition to CD34+ cells, Thy-1 was found to be expressed on a variable, very small number (< 1%) of CD34- mononuclear cells in BM, CB, and peripheral blood that were further characterized as CD3+ CD4+ lymphocytes. The restricted expression of Thy-1 on primitive hematopoietic cells is in agreement with a previous report (Baum et al., 1992. Proc. Natl. Acad. Sci. USA. 89:2804) in which Thy-1 expression was used to enrich for primitive hematopoietic cells from fetal tissue. Compared with those previous studies, we found Thy-1 expression on a larger proportion of CD34+ cells (25% in our study vs. 5% in Baum et al.) and furthermore performed studies on Thy-1 expression on CD34+ cells from CB, FL, and BM in relation to markers that are known to be differentially expressed on hematopoietic cells. Taken together our results indicate that Thy-1-specific antibody 5E10 is an attractive tool for further studies on the biology and purification of human stem cells.
Craig
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Terry Fox Laboratory, British Columbia Cancer Agency, Departments of Medicine, Pathology, and Medical Genetics, University of British Columbia, Vancouver, Canada.
Kay
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Cutler
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RL
Lansdorp
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PM
D000328:Adult; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis; D015703:Antigens, CD / Q000096:biosynthesis; D018952:Antigens, CD34; D000954:Antigens, Surface / Q000096:biosynthesis*; D001483:Base Sequence; D002478:Cells, Cultured; D003001:Cloning, Molecular; D004247:DNA; D005260:Female; D005312:Fetal Blood / Q000276:immunology; D006412:Hematopoietic Stem Cells / Q000276:immunology*; D006801:Humans; D016130:Immunophenotyping; D008099:Liver / Q000196:embryology / Q000276:immunology; D008562:Membrane Glycoproteins / Q000096:biosynthesis*; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D018800:Thy-1 Antigens
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D018952:Antigens, CD34; D000954:Antigens, Surface; D008562:Membrane Glycoproteins; D018800:Thy-1 Antigens; D004247:DNA