title: Microenvironmental cytokines and expression of erythroid heme metabolic enzymes.
abstract: In this study, we demonstrated that benzene and its metabolites, phenol and hydroquinone, were toxic to human burst-forming unit-erythroid (BFU-E) growth, hydroquinone being the most toxic. Phenol (10(-4) M) was also found to have a marked toxicity on stromal cell colony formation. BFU-E binding with human-tumor necrosis factor (rHu-TNF) was linear with the number of BFU-E colonies. Recombinant rHu-TNF suppressed BFU-E growth in a dose-dependent manner and this was reversed with anti-TNF antibody. Binding studies of rHu-TNF for human K562 cells indicated that K562 cells have a binding constant of approximately 1075 per cell. The heme pathway enzymes, uroporphyrinogen deaminase, and heme oxygenase activities were measured in BFU-E cultures exposed to iron, interleukins (1 and 2), and various lymphocyte and macrophage-conditioned media with or without hemin. In most instances, hemin was found to stimulate the heme synthetic pathway in the presence of these agents. Iron and adherent (macrophage) cell conditioned media (CM) were found to stimulate heme oxygenase activity. Macrophage CM was found to suppress erythropoiesis in contrast to phytohemagglutinin-stimulated leukocyte (PHAL)-CM, which enhanced erythroid growth. In addition, porphobilinogen deaminase levels were greater in 14-day cultures containing hemin plus PHAL-CM as compared with hemin alone. These results are discussed with respect to the generation of hematopoietic inhibitory-stimulatory factors by the marrow microenvironment and their effects on heme synthesis and degradation.
authors.affiliation: Department of Medicine, New York Medical College, Valhalla 10595.
authors.forename: A
authors.initials: A
authors.lastname: Brown
authors.forename: J D
authors.initials: JD
authors.lastname: Lutton
authors.forename: J
authors.initials: J
authors.lastname: Nelson
authors.forename: N G
authors.initials: NG
authors.lastname: Abraham
authors.forename: R D
authors.initials: RD
authors.lastname: Levere
mesh_terms: D000642:Ammonia-Lyases / Q000032:analysis*; D001554:Benzene / Q000494:pharmacology*; D001688:Biological Products / Q000378:metabolism / Q000494:pharmacology*; D001854:Bone Marrow Cells; D016207:Cytokines; D004900:Erythroblasts / Q000187:drug effects* / Q000201:enzymology; D004920:Erythropoiesis / Q000187:drug effects*; D006418:Heme / Q000096:biosynthesis*; D006419:Heme Oxygenase (Decyclizing) / Q000032:analysis*; D006427:Hemin / Q000494:pharmacology; D006801:Humans; D006873:Hydroquinones / Q000494:pharmacology*; D011163:Hydroxymethylbilane Synthase / Q000032:analysis*; D007501:Iron / Q000494:pharmacology; D007951:Leukemia, Myeloid / Q000473:pathology; D008264:Macrophages / Q000378:metabolism; D006899:Mixed Function Oxygenases / Q000032:analysis*; D009363:Neoplasm Proteins / Q000032:analysis; D010636:Phenols / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000494:pharmacology; D013601:T-Lymphocytes / Q000378:metabolism; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D001688:Biological Products; D016207:Cytokines; D006873:Hydroquinones; D009363:Neoplasm Proteins; D010636:Phenols; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D006418:Heme; D006427:Hemin; D007501:Iron; D006899:Mixed Function Oxygenases; D006419:Heme Oxygenase (Decyclizing); D011163:Hydroxymethylbilane Synthase; D000642:Ammonia-Lyases; D001554:Benzene; C031927:hydroquinone