Evidence for Distinct Intracellular Signaling Pathways in CD34+ Progenitor to Dendritic Cell Differentiation from a Human Cell Line Model

• Published in: The Journal of immunology (1950) 1999-03, Vol.162 (6), p.3237-3248
• Main Authors: St. Louis, Daniel C, Woodcock, Juliana B, Fransozo, Guido, Blair, Patrick J, Carlson, Louise M, Murillo, Maria, Wells, Mark R, Williams, Amanda J, Smoot, Douglas S, Kaushal, Sumesh, Grimes, Janelle L, Harlan, David M, Chute, John P, June, Carl H, Siebenlist, Ulrich, Lee, Kelvin P
• Format: Article
• Language: English
• Subjects: Adult; Antigens, CD34 - immunology; Antigens, Surface - biosynthesis; Apoptosis - immunology; Cell Differentiation - drug effects; Cell Differentiation - immunology; Cell Division - immunology; Cell Line; Cytokines - physiology; Dendritic Cells - cytology; Dendritic Cells - drug effects; Dendritic Cells - immunology; Dendritic Cells - metabolism; Enzyme Activation - immunology; Gene Expression Regulation - immunology; Hematopoietic Stem Cells - cytology; Hematopoietic Stem Cells - drug effects; Hematopoietic Stem Cells - immunology; Hematopoietic Stem Cells - metabolism; Humans; Immunophenotyping; Intracellular Fluid - immunology; Lymphocyte Activation - drug effects; Macromolecular Substances; Protein Kinase C - antagonists & inhibitors; Protein Kinase C - metabolism; Protein Kinase C - physiology; Proto-Oncogene Proteins - biosynthesis; Signal Transduction - immunology; T-Lymphocytes - immunology; Tetradecanoylphorbol Acetate - pharmacology; Transcription Factor RelB; Transcription Factors - biosynthesis
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.162.6.3237

Intracellular signals that mediate differentiation of pluripotent hemopoietic progenitors to dendritic cells (DC) are largely undefined. We have previously shown that protein kinase C (PKC) activation (with phorbol ester (PMA) alone) specifically induces differentiation of primary human CD34+ hemopoietic progenitor cells (HPC) to mature DC. We now find that cytokine-driven (granulocyte-macrophage CSF and TNF-alpha) CD34+ HPC-->DC differentiation is preferentially blocked by inhibitors of PKC activation. To further identify intracellular signals and downstream events important in CD34+ HPC-->DC differentiation we have characterized a human leukemic cell line model of this process. The CD34+ myelomonocytic cell line KG1 differentiates into dendritic-like cells in response to granulocyte-macrophage CSF plus TNF-alpha, or PMA (with or without the calcium ionophore ionomycin, or TNF-alpha), with different stimuli mediating different aspects of the process. Phenotypic DC characteristics of KG1 dendritic-like cells include morphology (loosely adherent cells with long neurite processes), MHC I+/MHC IIbright/CD83+/CD86+/CD14- surface Ag expression, and RelB and DC-CK1 gene expression. Functional DC characteristics include fluid phase macromolecule uptake (FITC-dextran) and activation of resting T cells. Comparison of KG1 to the PMA-unresponsive subline KG1a reveals differences in expression of TNF receptors 1 and 2; PKC isoforms alpha, beta I, beta II, and mu; and RelB, suggesting that these components/pathways are important for DC differentiation. Together, these findings demonstrate that cytokine or phorbol ester stimulation of KG1 is a model of human CD34+ HPC to DC differentiation and suggest that specific intracellular signaling pathways mediate specific events in DC lineage commitment.