Department of Internal Medicine, Yale School of Medicine, New Haven, CT 06520, USA.
Anal Biochem. 2010 May 15;400(2):251-8. doi: 10.1016/j.ab.2010.01.037. Epub 2010 Feb 1.
Diphenylmethane diisocyanate (MDI), the chemical commonly used as a cross-linking agent in commercial polyurethane production, is a well-recognized cause of asthma. Reaction products between MDI and "self" proteins are hypothesized to act as antigens capable of inducing airway inflammation and asthma; however, such MDI antigens remain incompletely understood. We used a variety of analytical methods to characterize the range of MDI-albumin reaction products that form under physiological conditions. Sites of MDI conjugation on antigenic MDI-albumin products, as defined by serum immunoglobulin G (IgG) from MDI-exposed workers, were determined by high-performance liquid chromatography (HPLC) followed by tandem mass spectrometry (MS/MS). The data identified 14 MDI conjugation sites (12 lysines and 2 asparagines) on human albumin and highlight reaction specificity for the second lysine in dilysine (KK) motifs, and this may be a common characteristic of "immune-sensitizing" chemicals. Several of the MDI conjugation sites are not conserved in albumin from other species, and this may suggest species differences in epitope specificity for self protein (albumin)-isocyanate conjugates. The study also describes new applications of contemporary proteomic methodology for characterizing and standardizing MDI-albumin conjugates destined for use in clinical research.
二苯甲烷二异氰酸酯（MDI），一种常用于商业聚氨酯生产的交联剂，是公认的哮喘病因。MDI 与“自身”蛋白质发生反应的产物被假设为能够诱导气道炎症和哮喘的抗原；然而，此类 MDI 抗原仍不完全了解。我们使用多种分析方法来描述在生理条件下形成的 MDI-白蛋白反应产物的范围。通过高效液相色谱（HPLC）和串联质谱（MS/MS），确定了抗原性 MDI-白蛋白产物上 MDI 结合位点，这些结合位点由暴露于 MDI 的工人的血清免疫球蛋白 G（IgG）定义。数据确定了人白蛋白上的 14 个 MDI 结合位点（12 个赖氨酸和 2 个天冬酰胺），并突出了二赖氨酸（KK）基序中第二个赖氨酸的反应特异性，这可能是“免疫致敏”化学物质的共同特征。其他物种的白蛋白中，有几个 MDI 结合位点并不保守，这可能表明自身蛋白（白蛋白）-异氰酸酯结合物的表位特异性存在物种差异。该研究还描述了用于描述和标准化用于临床研究的 MDI-白蛋白结合物的现代蛋白质组学方法的新应用。
