Differentiation associated modulation of the cytokine and chemokine expression pattern in human myeloid cell lines

Hematopoietic progenitor cell differentiation is associated with the expression of different sets of genes including those encoding membrane bound molecules and cytokines. While expression of the former has meticulously been linked to both lineage specificity and maturation stages and is routinely used in the diagnosis of human leukemias, the production of cytokines has not systematically been analyzed in this respect. Secretion of cyto- and chemokines by HPC has been discussed as a key element of autocrine regulation of cell differentiation and proliferation in normal and malignant hematopoietic cells. Hematopoietic cell lines and their in vitro generated mature progeny were used as a model to investigate the cytokine and chemokine expression pattern prior to and after induction of differentiation. We show that a variety of cytokines are produced by these cells either constitutively or upon stimulation. Low levels of TNF-alpha and IL-8 were widely expressed by immature and mature cells, while peak values of TNF-alpha were detected in promyelocytic NB4 cells, as reported previously. Induction of monocytic differentiation by various agents was associated with upregulation of IL-1 beta and IL-1ra expression, while a differentiation shift to the granulocytic lineage in the presence of retinoic acid (RA) led to a marked increase of macrophage chemoattractant protein-1 (MCP-1) producing cells. These data indicate that lineage determination as well as maturation of hematopoietic cells may not only be associated with expression of specific surface molecules but also with a distinct cytokine expression pattern. Further studies are necessary to show if this holds true for primary leukemic and normal hematopoietic cells.     

Cytokine and chemokine production by CD34+ haemopoietic progenitor cells: detection in single cells

In vitro expansion of haemopoietic progenitor cells (HPC), lineage-specific differentiation, and gene transfer are all based on in vitro culture systems using haemopoietic growth factors (HGF). A close control of the actual culture conditions, however, is difficult due to secondary mediators secreted by the heterogenous population of mature and immature cells in culture. Although monocytes and granulocytes have already been identified as active producers, this study specifically addressed the role of CD34⁺ progenitor cells in this respect. Using an immunostaining method that enables simultaneous detection of cytokines and phenotype, 56±6% CD34⁺ peripheral blood progenitor cells (PBPC) were found to contain cytoplasmic IL-8 after stimulation with phorbol myristate acetate+ionomycin for 90 min, 19±4% stained positive after TNF-α induction (20 h), and 7±1% expressed IL-8 in the presence of culture medium alone. Intra-cytoplasmic TNF-α and IL-1β were detected at lower frequency, and <1% of CD34⁺ cells expressed IL-1ra or IL-6, whereas IL-1α, IL-10 and G-CSF were not detected. Thus, CD34⁺ HPC are able to synthesize chemo- and cytokines that may operate in an auto- or paracrine manner to modulate in vivo as well as in vitro growth and differentation of haemopoietic cells.     

Spontaneous variations in the cell population of a T-cell lymphoma during tissue culture and transplantation.

Immunologically induced T-cell lymphomas were kept for long period fo time in isotransplantation and in tissue culture. Initially, a certain number of cells within the tumor showed differentiation towards histiocytes. These disappeared completely after about the twentieth graft generation when the tumor changed toward a more atypical and more uniform neoplasm. That change was correlated with a decrease in transplantability, a limited growth in tissue culture, and a decrease in density of theta antigens on tumor cell membranes. While the original tumor and early grafts contained occasional C-type particles, these were never demonstrated in late tumor grafts. The possible implications of these changes are discussed.     

Spontaneous variations in the cell population of a T-cell lymphoma during tissue culture and transplantation

Summary Immunologically induced T-cell lymphomas were kept for long periods of time in isotransplantation and in tissue culture. Initially, a certain number of cells within the tumor showed differentiation towards histiocytes. These disappeared completely after about the twentieth graft generation when the tumor changed toward a more atypical and more uniform neoplasm. That change was correlated with a decrease in transplantability, a limited growth in tissue culture, and a decrease in density of theta antigens on tumor cell membranes. While the original tumor and early grafts contained occasional C-type particles, these were never demonstrated in late tumor grafts. The possible implications of these changes are discussed.

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Spontanvariationen in der Zellpopulation eines T-Zell Lymphoms in Zellkultur und nach Isotransplantation

Zusammenfassung Ein immunologisch induziertes T-Zell Lymphom der Maus wurde über längere Zeit in der Zellkultur und in Isotransplantation gehalten. Zu Beginn war eine gewisse Differenzierungspotenz einzelner Zellen im Tumor in Richtung auf Histiocyten erkennbar, die später zugunsten einer mehr homogenen atypischen Lymphoblastenpopulation verloren ging. Diese Änderung wurde besonders in transplantierten Tumoren nach der 20. Generation erkennbar. Gleichzeitig kam es zu einer Zunahme bestimmter Cytoplasmastrukturen und zu einer Abnahme der Theta-Antigen Häufigkeit sowie zu einer herabgesetzten Angehrate des Tumors bei Transplantation und zu begrenztem Wachstum in der Zellkultur. Anfangs beobachtete C-Typ Partikel ließen sich später nicht mehr nachweisen. Die mögliche Bedeutung dieser Befunde wird diskutiert.

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The investigations are supported by the German Science Foundation and by the Volkswagen Foundation.

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We are indebded to Dr. Gregory T. O'Conor, National Cancer Institute, NIH, U.S.A., for assistence in some of the ultrastructural work.