MOLECULAR MECHANISM OF IMMUNOTOXIC ACTION OF TCDD & DTT

一些环境污染物，如2.3.7.8 四氯二苯并双恶英和1.1.1-三氯-2-(2- 氯苯基)-2-(4-氯苯基)乙烷(o，p‘DTT)已知具有 类固醇作用和免疫毒性作用在动物和 人类。这些化合物与细胞内受体蛋白结合。 与糖皮质激素和雌激素的作用相似。自.以来 免疫系统在宿主抵抗中起着至关重要的作用 动态平衡，外源生物诱导的免疫调节可能 是对健康产生负面影响的基础。单核/巨噬细胞 在启动免疫调节方面有各种关键功能， 通过抗原提呈、单核细胞因子产生和 形成花生四烯酸代谢物，这些功能是 已知受到糖皮质激素和雌激素的影响。在 在这里提出的项目，我们的目标是研究分子 类固醇和外源物质对血管内皮细胞功能的作用机制 单核/巨噬细胞和随后的细胞免疫。 具体目的是检查(A)这些外来生物和 类固醇与相同或不同的受体结合，(B)无论它们是 诱导或阻断第二信使蛋白的合成 类固醇，(C)它们对IL的基因表达有什么作用 1、肿瘤坏死因子、人类白细胞抗原-DR和脂皮质素，以及(D)这些对IL的影响 1、肿瘤坏死因子、人类白细胞抗原-DR和脂皮质蛋白的改变归因于 花生四烯酸代谢或异种生物基因调控- 受体复合体或两者兼而有之。外源生物和类固醇将是 与分离的人外周血体外孵育 单核细胞/巨噬细胞在缺乏和存在特异性和 非特异性激活剂，如伽马-LFN、脂多糖和佛波酯。 花生四烯酸代谢产物的高效液相色谱定量分析 高效液相色谱。约束性分析将是 通过竞争性配基结合分析进行。身份识别 新诱导的蛋白质将以二维方式进行 ~(35)S蛋氨酸的电泳法及其生物学作用 对单核细胞和T淋巴细胞进行检测。这项规定 白介素1、肿瘤坏死因子、脂皮质素(推测为第二信使 糖皮质激素)和人类白细胞抗原-DR基因的表达将被研究 Northern Blot以它们的cDNA克隆为探针。利用 外源生物免疫毒性机制的研究进展 免疫调节导致免疫抑制的机制 (获得性免疫缺陷)，我们建议建立机制 外源物质对生物化学和细胞功能作用的研究 单核/巨噬细胞。

Some environmental contaminants such as 2.3.7.8 tetrachlorodibenzoparadioxin (TCDD) and 1.1.1-trichloro-2-(2- chlorophenyl)-2-(4-chlorophenyl)ethane (o,p'DTT), are known to have steroidal actions as well as immunotoxic actions in animals and humans. These compounds bind to intracellular receptor proteins similar to those for glucocorticoids and estrogens. Since the immune system plays a crucial role in host resistance and homeostasis, the immunomodulation induced by the xenobiotics may be the basis for adversed health effects. Monocytes/macrophages have various key functions in initiating the immune regulation, mediating through antigen presentation, monokine production, and formation of arachidonate metabolites, and these functions are known to be affected by glucocorticoids and estrogens. In the projects proposed herein, we aim to investigate the molecular mechanism of actions of steroids and xenobiotics on function of monocytes/macrophages and subsequently, of cell mediated immunity. The specific aims are to examine (a) whether these xenobiotics and steroids bind to the same or different receptors, (b) whether they induce or block the synthesis of second messenger proteins of steroids, (c) what are their actions on the gene expression of IL 1, TNF, HLA-DR and lipocortin and (d) whether these effects on IL 1, TNF, HLA-DR and lipocortin are attributed to alteration of arachidonate metabolism or of gene regulation by the xenobiotic- receptor complex or both. Xenobiotics and steroids will be incubated in vitro with fractionated human peripheral monocytes/macrophages in the absence and presence of specific and nonspecific activators such as gamma-lFN, LPS and phorbol esters. Metabolites of arachidonate will be quantitatively analyzed by high performance liquid chromatography. The binding analysis will be performed by competitive ligand binding assays. Identification of newly induced proteins will be carried out by two dimensional electrophoresis using (35S)methionine and their biological actions on monocytes and T lymphocytes will be examined. The regulation of IL 1, TNF, lipocortin (putative second messenger of glucocorticoids) and HLA-DR gene expression will be investigated by the Northern Blot using their cDNA clones as probes. To exploit not only the mechanism of immunotoxicity of xenobiotics but also the mechanism of immunoregulation leading to the immunosuppression (acquired immune deficiency), we propose to establish the mechanism of action of xenobiotics on the biochemical and cellular functions of monocytes/macrophages.