title: Differentiation of functional dendritic cells and macrophages from human peripheral blood monocyte precursors is dependent on expression of p21 (WAF1/CIP1) and requires iron.
abstract: Iron is required for monocyte/macrophage differentiation of HL-60 leukaemia cells. Differentiation requires induction of the cyclin-dependent kinase inhibitor p21 (WAF1/CIP1), and cell cycle arrest at the G1/S checkpoint. With iron depletion, p21 induction and differentiation are blocked. To establish the roles of iron and p21 in normal monocyte/macrophage differentiation, we examined generation of dendritic cells (DCs) and macrophages from peripheral monocytes. Monocytes were cultured with interleukin 4 and granulocyte-macrophage colony-stimulating factor (GM-CSF), then treated with lipopolysaccharide to produce DCs or with M-CSF to produce macrophages. Iron deprivation was induced by desferrioxamine (DF). Monocyte-derived DCs had characteristic phenotype and morphology, and stimulated proliferation of naïve allogeneic T lymphocytes. In contrast, DCs generated under iron deprivation were phenotypically undifferentiated and did not stimulate T cells. Similarly, macrophages expressed a characteristic phenotype and morphology, and phagocytosed latex beads, but macrophages generated under iron deprivation failed to develop a mature phenotype and had impaired phagocytosis. Iron deprivation blocked induction of p21 (WAF1/CIP1) expression in both DC and macrophage cultures. Furthermore, p21 antisense oligonucleotides, but not sense oligonucleotides, inhibited both DC and macrophage differentiation. These data indicate that a key role of iron in haematopoiesis is to support induction of p21 which, in turn, is required for DC and macrophage differentiation.
authors.affiliation: Department of Medicine/Hematology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA.
authors.forename: Joan L
authors.initials: JL
authors.lastname: Kramer
authors.forename: Ioannis
authors.initials: I
authors.lastname: Baltathakis
authors.forename: Orlando S F
authors.initials: OS
authors.lastname: Alcantara
authors.forename: David H
authors.initials: DH
authors.lastname: Boldt
mesh_terms: D018929:Cell Culture Techniques / Q000379:methods; D002454:Cell Differentiation / Q000502:physiology; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism*; D003713:Dendritic Cells / Q000166:cytology* / Q000378:metabolism; D006410:Hematopoiesis / Q000502:physiology; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000378:metabolism; D006801:Humans; D016130:Immunophenotyping; D007501:Iron / Q000502:physiology*; D008264:Macrophages / Q000166:cytology* / Q000378:metabolism; D009000:Monocytes / Q000166:cytology / Q000378:metabolism
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D007501:Iron