title: CD84 expression on human hematopoietic progenitor cells.
abstract: OBJECTIVE
  CD84 is a member of the CD2 subgroup of the immunoglobulin receptor superfamily. Members of this family have been implicated in the activation of T cells and NK cells. Expression of CD84 was originally described on most mononuclear blood cells as well as platelets. To elucidate its presence on other blood cell types, we analyzed the expression pattern of CD84 on human immature CD34+ and mature hematopoietic cells.
  
  
  METHODS
  Expression analysis was carried out by flow cytometry. The differentiation potential of CD84+ progenitor cells was assessed by colony-forming assays and long-term cultures. RT-PCR was used to analyze CD84 mRNA isoforms.
  
  
  RESULTS
  In addition to monocytes, macrophages, B cells, and some T cells, CD84 is expressed on the cell surface of the majority of granulocytes. In addition, 64%+/-5% of CD34+ progenitor cells isolated from peripheral blood and 30.5%+/-5% from bone marrow of healthy volunteers also express CD84. The majority of CD34+ cells coexpressing lineage antigens were CD84+. In methylcellulose CD34+CD84+ cells formed primarily erythroid colonies, whereas myeloid or mixed colonies were scarce. The frequency of long-term culture-initiating cells in peripheral blood was approximately fivefold higher in CD34+CD84- vs CD34+CD84+ cells. In short-term cultures, 95% of the initially CD34+CD84- cells became CD84+ after 72 hours.
  
  
  CONCLUSIONS
  CD84 is expressed on cells from almost all hematopoietic lineages and on CD34+ hematopoietic progenitor cells. The proliferative potential of CD34+ cells decreases with increasing CD84 expression, suggesting that CD84 serves as a marker for committed hematopoietic progenitor cells.
authors.affiliation: Abteilung für Hämatologie und Internistische Onkologie and Institut für Pathologie, University of Regensburg, Regensburg, Germany. matthias.zaiss@klinik.uni-regensburg.de
authors.forename: Matthias
authors.initials: M
authors.lastname: Zaiss
authors.forename: Christian
authors.initials: C
authors.lastname: Hirtreiter
authors.forename: Michael
authors.initials: M
authors.lastname: Rehli
authors.forename: Annegret
authors.initials: A
authors.lastname: Rehm
authors.forename: Leoni A
authors.initials: LA
authors.lastname: Kunz-Schughart
authors.forename: Reinhard
authors.initials: R
authors.lastname: Andreesen
authors.forename: Burkhard
authors.initials: B
authors.lastname: Hennemann
mesh_terms: D015703:Antigens, CD / Q000096:biosynthesis / Q000276:immunology*; D015415:Biomarkers; D002455:Cell Division; D019070:Cell Lineage / Q000276:immunology*; D002478:Cells, Cultured; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000276:immunology*; D006801:Humans; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000276:immunology*; D000071176:Signaling Lymphocytic Activation Molecule Family
chemical_list: D015703:Antigens, CD; D015415:Biomarkers; C498970:CD84 protein, human; D008562:Membrane Glycoproteins; D000071176:Signaling Lymphocytic Activation Molecule Family