Yamaguchi K, Matulka R A, Shneider A M, Toselli P, Trombino A F, Yang S, Hafer L J, Mann K K, Tao X J, Tilly J L, Near R I, Sherr D H
Department of Environmental Health, Boston University Schools of Medicine and Public Health, Massachusetts, USA.
Toxicol Appl Pharmacol. 1997 Dec;147(2):190-203. doi: 10.1006/taap.1997.8263.
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.
大量研究表明，多环芳烃（PAH）通过改变B细胞和T细胞的功能来抑制免疫。相对较少的研究评估了这些常见环境化学物质对未成熟淋巴细胞的影响。在本研究中，采用长期原代骨髓培养来研究一种典型的PAH和芳烃受体（AhR）激动剂7,12 - 二甲基苯并[a]蒽（DMBA）对未成熟B淋巴细胞的影响。在这个系统中，未成熟的前B细胞维持在由骨髓基质细胞提供的支持性微环境中。此处呈现的结果表明：（1）原代骨髓培养物暴露于DMBA会导致前B细胞通过凋亡死亡；（2）显著低剂量的DMBA（≥10⁻⁸ M）可诱导前B细胞凋亡；（3）在长期培养中，通过原位杂交、逆转录 - 聚合酶链反应（RT - PCR）和免疫印迹测定，骨髓基质细胞而非前B细胞表达AhR mRNA和蛋白；（4）通过免疫组织化学评估，新鲜分离的未分级骨髓细胞而非纯化的骨髓B细胞表达AhR蛋白；（5）α - 萘黄酮，一种竞争性AhR抑制剂和细胞色素P450拮抗剂，可完全阻断原代骨髓培养物中DMBA诱导的前B细胞凋亡；（6）体内注射DMBA或苯并[a]芘会导致骨髓细胞凋亡，这与围绕基质成分聚集的造血细胞死亡一致。这些结果表明程序性细胞死亡是DMBA介导的免疫抑制的潜在机制，并表明前B细胞死亡受与AhR⁺骨髓基质细胞的局部相互作用影响。
