title: Myb-transformed hematopoietic cells as a model for monocyte differentiation into dendritic cells and macrophages.
abstract: Immune induction is effected through the interaction of antigen-presenting cells with specific receptors on the surface of thymus-derived lymphocytes. Cells most able to ingest, process, and present antigen appear to be related to the mononuclear phagocyte/neutrophil series. For example dendritic cells (DC) can be found in colonies of GM-CSF-responsive bone marrow cells, and under experimental conditions are routinely expanded as a population in vitro from GM-CSF-responsive progenitor cells. To address the question of DC lineage and to determine what genes are involved in lineage commitment, we have generated a series of GM-CSF-responsive cell lines that can be induced to differentiate in a homogeneous manner in vitro. The cloned cell lines are derived from 12-day fetal liver and are transformed with a truncated form of c-myb, which lacks the normal autoregulatory sequences. As far as we know, these myb-transformed hemopoi-etic cells (MTHC) differ from normal only in the unregulated expression of myb, a gene whose expression is obligatory for proliferation of hemopoietic cells. MTHC in the presence of TNF-alpha and IL-4 will differentiate into cells that have many of the properties of macrophages. When the same MTHC lines are exposed to TNF-alpha in combination with IFN-gamma, the cells instead become DC. The differentiated DC are potent presenters of antigen in mixed lymphocyte reactions and of soluble antigen to specific T cell lines. Thus, cells with the properties of both macrophages and DC can be derived from a single type of GM-CSF-responsive progenitor cell. We have used this MTHC system to analyze differences in gene expression as the cells mature along the DC and macrophage pathways. A distinctive pattern of differentially expressed cDNAs is evident where macrophage-specific cDNAs are homologous to genes encoding cytoskeletal and cell-surface proteins, whereas the DC-specific cDNAs are homologous to signaling, chemokine, and IFN-gamma-inducible genes. We discuss the utility of MTHC in analyzing the relationships between DC and macrophages, and suggest that DC and macrophages represent extreme phenotypes in a spectrum of antigen handling cells that are somewhat interchangeable, depending on their immediate environment.
authors.affiliation: Experimental Haematology Group, John Curtin School of Medical Research, Australian National University, Canberra, ACT.
authors.forename: J L
authors.initials: JL
authors.lastname: Banyer
authors.forename: A J
authors.initials: AJ
authors.lastname: Hapel
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000145:classification / Q000166:cytology; D002454:Cell Differentiation; D002461:Cell Line, Transformed; D019070:Cell Lineage; D003713:Dendritic Cells / Q000166:cytology* / Q000276:immunology; D006412:Hematopoietic Stem Cells; D006801:Humans; D008264:Macrophages / Q000166:cytology* / Q000276:immunology; D008954:Models, Biological; D009000:Monocytes / Q000166:cytology* / Q000276:immunology; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D020598:Proto-Oncogene Proteins c-myb; D015534:Trans-Activators / Q000235:genetics*
chemical_list: D011518:Proto-Oncogene Proteins; D020598:Proto-Oncogene Proteins c-myb; D015534:Trans-Activators