title: Induction of PreB cell apoptosis by 7,12-dimethylbenz[a]anthracene in long-term primary murine bone marrow cultures.
abstract: Numerous studies demonstrate that polycyclic aromatic hydrocarbons (PAH) suppress immunity by modifying the function of both B and T cells. Relatively few studies have assessed the effects of these common environmental chemicals on immature lymphocytes. In the present study, long-term primary bone marrow cultures were employed to investigate the effects of a prototypic PAH and aryl hydrocarbon receptor (AhR) agonist, 7,12-dimethylbenz[a]anthracene (DMBA), on immature B lymphocytes. In this system, immature preB cells are maintained in a supportive microenvironment provided by bone marrow stromal cells. Results presented here demonstrate that (1) exposure of primary bone marrow cultures to DMBA results in preB cell death by apoptosis; (2) notably low doses of DMBA (> or = 10(-8) M) induce preB cell apoptosis; (3) in long-term cultures, bone marrow stromal cells, but not preB cells, express AhR mRNA and protein as determined by in situ hybridization, RT-PCR, and immunoblotting; (4) freshly isolated unfractionated bone marrow cells, but not purified bone marrow B cells, express AhR protein as assessed by immunohistochemistry; (5) alpha-naphthoflavone, a competitive AhR inhibitor and cytochrome P450 antagonist, completely blocks DMBA-induced preB cell apoptosis in primary bone marrow cultures; and (6) DMBA or benzo[a]pyrene injection in vivo results in bone marrow cell apoptosis consistent with the death of hematopoietic cells clustered around stromal elements. The results implicate programmed cell death as a mechanism underlying DMBA-mediated immunosuppression and suggest that preB cell death is influenced by local interactions with AhR+ bone marrow stromal cells.
authors.affiliation: Department of Environmental Health, Boston University Schools of Medicine and Public Health, Massachusetts, USA.
authors.forename: K
authors.initials: K
authors.lastname: Yamaguchi
authors.forename: R A
authors.initials: RA
authors.lastname: Matulka
authors.forename: A M
authors.initials: AM
authors.lastname: Shneider
authors.forename: P
authors.initials: P
authors.lastname: Toselli
authors.forename: A F
authors.initials: AF
authors.lastname: Trombino
authors.forename: S
authors.initials: S
authors.lastname: Yang
authors.forename: L J
authors.initials: LJ
authors.lastname: Hafer
authors.forename: K K
authors.initials: KK
authors.lastname: Mann
authors.forename: X J
authors.initials: XJ
authors.lastname: Tao
authors.forename: J L
authors.initials: JL
authors.lastname: Tilly
authors.forename: R I
authors.initials: RI
authors.lastname: Near
authors.forename: D H
authors.initials: DH
authors.lastname: Sherr
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000818:Animals; D017209:Apoptosis; D001402:B-Lymphocytes / Q000187:drug effects* / Q000502:physiology; D002478:Cells, Cultured; D006412:Hematopoietic Stem Cells / Q000187:drug effects* / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D012333:RNA, Messenger / Q000378:metabolism; D018336:Receptors, Aryl Hydrocarbon / Q000235:genetics / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D018336:Receptors, Aryl Hydrocarbon; D015127:9,10-Dimethyl-1,2-benzanthracene