title: The growth response of Lin-Thy-1+ hematopoietic progenitors to cytokines is determined by the balance between synergy of multiple stimulators and negative cooperation of multiple inhibitors.
abstract: The present studies investigated the balance of positive and negative growth signals in direct regulation of hematopoiesis. Interleukin-3 (IL-3) combined with Steel factor (SLF) optimally stimulated proliferation of Lin-Thy-1+ murine bone marrow progenitors in single-cell assays, and that proliferation was inhibited more than 90% by transforming growth factor-beta 1 (TGF-beta 1). Colony-stimulating factor-1 (CSF-1), granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-1, or IL-6 as a third stimulatory growth factor was incapable of counteracting the TGF-beta 1-mediated inhibition of IL-3-plus-SLF-stimulated growth, while G-CSF slightly enhanced the number of TGF-beta 1-resistant clones. As a fourth factor, only IL-1 could partially overcome the TGF-beta 1-induced growth inhibition. While the presence of a cocktail of five additional stimulatory growth factors did not enhanced the frequency of single Lin-Thy-1+ progenitors proliferating in response to IL-3 plus SLF, the number of responding progenitors in the presence of TGF-beta 1 was enhanced nine-fold. Furthermore, tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma), but not macrophage inflammatory protein-1 alpha (MIP-1 alpha), cooperated with TGF-beta 1 to reverse the proliferative effects of multiple stimulatory cytokines, resulting in 76% inhibition. Thus, the direct effects of single inhibitory factors on hematopoietic progenitor cell growth can be reversed by multiple stimulatory growth factors, and negative growth factors can directly cooperate to suppress progenitor cell growth stimulated by multiple positive-acting factors.
authors.affiliation: Department of Immunology, Norwegian Radium Hospital, Oslo.
authors.forename: S E
authors.initials: SE
authors.lastname: Jacobsen
authors.forename: F W
authors.initials: FW
authors.lastname: Ruscetti
authors.forename: M
authors.initials: M
authors.lastname: Ortiz
authors.forename: J M
authors.initials: JM
authors.lastname: Gooya
authors.forename: J R
authors.initials: JR
authors.lastname: Keller
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells; D002455:Cell Division / Q000187:drug effects; D054407:Chemokine CCL4; D016207:Cytokines / Q000494:pharmacology*; D004357:Drug Synergism; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006410:Hematopoiesis / Q000187:drug effects; D016298:Hematopoietic Cell Growth Factors / Q000494:pharmacology; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D007371:Interferon-gamma / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D007377:Interleukin-3 / Q000494:pharmacology; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D019402:Macrophage Inflammatory Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D015846:Monokines / Q000494:pharmacology; D019089:Stem Cell Factor; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D054407:Chemokine CCL4; D016207:Cytokines; D016298:Hematopoietic Cell Growth Factors; D007375:Interleukin-1; D007377:Interleukin-3; D019402:Macrophage Inflammatory Proteins; D015846:Monokines; D019089:Stem Cell Factor; D016212:Transforming Growth Factor beta; D014409:Tumor Necrosis Factor-alpha; D016173:Macrophage Colony-Stimulating Factor; D007371:Interferon-gamma; D016178:Granulocyte-Macrophage Colony-Stimulating Factor