求翻译一篇英文化学文献

求翻译一篇英文化学文献

Quantifying the Cluster of Differentiation 4 Receptor Density on Human T Lymphocytes Using Multiple Reaction Monitoring Mass Spectrometry
多反应监测质量光谱法应用于人类T淋巴细胞量化分化抗原簇4受体密度
ABSTRACT: Cluster of differentiation 4 (CD4) is an important glycoprotein containing four extracellular domains, a transmembrane portion and a short intracellular tail. It locates on the surface of various types of immune cells and performs a critical role in multiple cellular functions such as signal amplification and activation of T cells. It is well-known as a clinical cell surface protein marker for study of HIV progression and for defining the T helper cell population in immunological applications. Moreover, CD4 protein has been used as a biological calibrator for quantification of other surface and intracellular proteins. However, flow cytometry, the conventional method of quantification of the CD4 density on the T cell surface depends on antibodies and has suffered from variables such as antibody clones, the fluorophore and conjugation chemistries, the fixation conditions, and the flow cytometric quantification methods used. In this study, we report the development of a highly reproducible nano liquid chromatography−multiple reaction monitoring mass spectrometry-based quantitative method to quantify the CD4 receptor density in units of copy number per cell on human CD4+ T cells. The method utilizes stable isotope-labeled full-length standard CD4 as an internal standard to measure
endogenous CD4 directly, without the use of antibodies. The development of the mass spectrometry-based approach of CD4 protein quantification is important as a complementary strategy to validate the analysis from the cytometry-based conventional method. It also provides new support for quantitative understanding and advanced characterization of CD4 on CD4+ T cells.

摘要：集群分化4(CD4)是一种重要的糖蛋白，它包含四个胞外区域,横跨膜的部分和短的细胞内尾巴。它位于各种类型免疫细胞的表面，在多种细胞功能中扮演重要角色，像细胞信号放大和激活的T细胞。众所周知的是作为研究艾滋病病程的临床细胞表面蛋白标记和在免疫学应用程序中定义辅助T细胞数量。除此之外，CD4细胞蛋白质也已被用作其他表面和胞内蛋白量化的生物校准器。但是，流式细胞，传统量化CD4 T细胞表面密度的方法取决于抗体和并且会受到像抗体克隆、荧光团和结合化学、固定条件以及以前流式细胞定量方法等变量带来的改变。在这项研究中，我们报道一种人类CD4 + T细胞中量化CD4受体密度在每个细胞的拷贝数的高度可再生的纳米液相色谱 - 多反应监测质谱为基础的定量方法的发展。该方法利用稳定同位素标记的全长标准CD4作为内部标准来直接衡量内源性CD4，而不需要使用抗体。 以CD4质谱为基础的蛋白定量方法的发展，作为一个重要的补充战略来验证分析以流式细胞仪为基础的传统方法。它还提供

了定量的理解和CD4在CD4 + T细胞上高级鉴定的新支持。
Cluster of differentiation 4 (CD4) is a glycoprotein that locates on the surface of immune cells such as T helper cells, monocytes, macrophages, and dendritic cells. As a coreceptor, CD4 amplifies the signal generated by the T cell receptor, which is essential for activation of many molecules involved in the signaling cascade of an activated T cell. In human T lymphocytes, CD4 receptor protein is encoded by the CD4 gene1and has four distinct extracellular domains (D1 to D4), a transmembrane portion, and a short intracellular tail.2The use of antihuman CD4 monoclonal antibodies generated against the four extracellular domains has been widely used to define T helper cells in immunophenotyping. Although the number of CD4+ T cells decreases in the progression of HIV-1 viral infection deriving from the gp120 viral protein binding to the CD4 receptor, Poncelet et al. reported that the surface CD4 density still remained constant on T helper cells of HIV-1 infected individuals.3Since then, multiyear research has supported the theory that CD4 expression/density can be used as a biological calibrator for quantification of other surface and intracellular proteins.4
分化4 （ CD4）的集群是一种糖蛋白，位于免疫细胞如T辅助细胞，单核细胞，巨噬细胞和树突状细胞的表面。作为一个辅助受体，CD4放大由T细胞受体产生的信号，它对很多分子的活化作用很重要包括信号级联激活T细胞。人类T淋巴细胞， CD4的受体蛋白质是由编码CD4 基因并且有四个不同的胞外结构域（D1到D4） ，跨膜部分和短的胞内尾巴。利用抗人CD4单克隆抗体在4各细胞外结构域的繁殖，已被广泛地被用于在免疫表型上定义辅助性T细胞。尽管CD4 + T细胞的数目在HIV -1病毒感染中减少，HIV -1病毒感染来源于病毒的gp120蛋白结合到CD4受体，蓬斯莱等。报告说，表面CD4的密度在艾滋病毒感染者的T辅助细胞上仍保持不变。从此以后，多年的研究支持了CD4表达/密度可用作生物校准器用于其它表面和细胞内蛋白质量化的这一理论。
Quantitative multicolor flow cytometry incorporating anti- bodies and a fluorescence detection method has played a critical role in clinical diagnostics and immunotherapies. Though the ultimate objective of quantitative flow cytometry is to measure the number of antigens or ligand binding sites associated with a cell, the task is carried out by measuring the number of antibodies bound per cell (ABC). It is critically important to produce biological cell reference materials that bear well-characterized protein markers such as CD4 for the trans-formation of a calibrated linear fluorescence intensity scale of a flow cytometer channel to a biologically meaningful ABC scale.7The quality of the cytometric measurements is affected by variables such as antibody clones, the fluorophore and conjugation chemistries, the fixation conditions, and the flow cytometric quantification methods used.4,8−11Hence, in addition to characterizing candidate reference cell preparations that use antibody-based cytometric methods,12it is necessary to develop a complementary approach to validate the absolute quantification of reference marker proteins such as CD4 without the use of antibodies.
定量多色流式细胞结合体和荧光检测方法在临床诊断和免疫治疗中起到了至关重要的作用。虽然定量流式细胞仪最终目标是测量抗原或与细胞结合配体结合位点的数目，该任务的完成是通过测量每个细胞（ ABC）抗体结合的数目。这对于