ACTIVATION OF HUMAN MONOCYTES BY LIPOPOLYSACCHARIDE--MECHANISM OF PRIMING

细菌脂多糖（LPS）是一种有效的刺激剂， 单核细胞和巨噬细胞。 由LPS诱导的功能对于 有效宿主防御，但LPS也可诱导病理性 并发症时，反应继续未经检查。 的长期目标 本项目旨在阐明LPS参与的分子事件， 刺激人单核细胞。 这些研究的重点是 调节有效的生物活性细胞因子（如 肿瘤坏死因子、干扰素、白细胞介素-1）。 我们目前的具体兴趣是启动的机制， 单核细胞导致随后的LPS显着增强 应答 在干扰素-γ或干扰素-γ中培养后发生引发。 （IFN-γ）或粒细胞-巨噬细胞集落刺激因子（GM-CSF）。 引发是LPS诱导的IFN-α产生的绝对要求， 也导致TNF产生的显著增强。分析 这些细胞因子的特异性RNA表明，它们的增强 在引发的单核细胞中的表达发生在RNA水平。 有一些 证据表明对TNF mRNA表达的影响是转录的; 核连续分析表明LPS诱导转录， 这是加强了启动，但没有到一定程度，解释了巨大的 增加mRNA的积累。 引发也对NF-κ B有显著影响。 kB转录因子激活; NF-kB与 介导LPS诱导的转录反应。 目前的重点 在实验室中的作用是调节特定mRNA的稳定性。 的 研究中的细胞因子（TNF，IFN）在具有 被认为与mRNA不稳定性相关的3 '-侧翼序列。 TNF mRNA半衰期的详尽研究表明， 导致TNF mRNA稳定性的显著增加。 进一步研究 旨在阐明潜在的RNA-蛋白质相互作用， 这种现象。 一系列平行的研究审查了 单核细胞-T细胞界面重要的新细胞因子的表达 反应，IL-12。 这些研究表明，IFN-γ选择性地 用于LPS诱导的IL-12 p35和p40链表达的引物。

Bacterial lipopolysaccharide (LPS) is a potent stimulatory agent for monocytes and macrophages. The functions induced by LPS are critical to effective host defense, but LPS can also induce pathological complications when responses continue unchecked. The long-term goal of this project is to elucidate molecular events that are involved in LPS stimulation of human monocytes. The focus of these studies is the regulation of the production of potent, bioactive cytokines (such as tumor necrosis factor, interferon, interleukin-1) in response to LPS. Our current specific interest is in the mechanism(s) of priming of monocytes which results in marked enhancement of subsequent LPS responses. Priming occurs following culture in either interferon-gamma (IFN--) or granulocyte-macrophage colony-stimulating factor (GM-CSF). Priming is an absolute requirement for LPS-induced IFN-a production, and results in substantial enhancement of TNF production as well. Analysis of specific RNA for these cytokines indicated that their enhanced expression in primed monocytes occurs at the RNA level. There is some evidence that the effects on TNF mRNA expression are transcriptional; nuclear run-on analysis suggested that LPS induces trancription and that this is enhanced by priming, but not to a degree that explains the vast increase in mRNA accumulation. Priming also has dramatic effects on NF- kB transcription factor activation; NF-kB has been implicated in mediating LPS-induced transcriptional responses. The current emphasis in the laboratory is on the regulation of specific mRNA stability. The cytokines under study (TNF, IFN) are unique with respect to possessing 3'-flanking sequences thought to be associated with mRNA instability. Exhaustive studies of mRNA half-life of TNF demonstrated that priming results in a substantial increase in TNF mRNA stability. Further studies are designed to elucidate potential RNA-protein interactions involved in this phenomenon. A parallel series of studies has examined the expression of an important new cytokine that interfaces monocyte-T cell responses, IL-12. These studies have shown that IFN-gamma selectively primes for the expression of LPS-induced IL-12 p35 and p40 chains.