Department of Physics, University of Gothenburg, Gothenburg, Sweden.
Chem Res Toxicol. 2011 May 16;24(5):737-43. doi: 10.1021/tx200030y. Epub 2011 Apr 12.
Allergic contact dermatitis is the most prevalent form of human immunotoxicity. It is caused by reactive low molecular weight chemicals, that is, haptens, coming in contact with the skin where hapten-peptide complexes are formed, activating the immune system. By using sensitizing fluorescent thiol-reactive haptens, that is, bromobimanes, we show how keratinocytes respond to hapten exposure in vitro and reveal, for the first time in a living system, an exact site of haptenation. Rapid internalization and reaction of haptens with keratin filaments were visualized. Subsequently, keratinocytes respond in vitro to hapten exposure by release of membrane blebs, which contain haptenated keratins 5 and 14. Particularly, cysteine 54 of K5 was found to be a specific target. A mechanism is proposed where neoepitopes, otherwise hidden from the immune system, are released after hapten exposure via keratinocyte blebbing. The observed expulsion of modified keratins by keratinocytes in vitro might play a role during hapten sensitization in vivo and should be subject to further investigations.
变应性接触性皮炎是最常见的人类免疫毒性形式。它是由反应性低分子量化学物质，即半抗原，与皮肤接触引起的，在那里形成半抗原-肽复合物，激活免疫系统。通过使用敏化荧光硫醇反应性半抗原，即溴代丁烷，我们展示了角质细胞如何在体外对半抗原暴露做出反应，并首次在活体系统中揭示了半抗原化的确切部位。快速内化和半抗原与角蛋白丝的反应被可视化。随后，角质细胞通过释放含有半抗原化角蛋白 5 和 14 的膜泡来体外响应半抗原暴露。特别地，发现 K5 的半胱氨酸 54 是一个特定的靶标。提出了一种机制，其中新表位在半抗原暴露后通过角质细胞泡状化从免疫系统中释放出来。在体外观察到的角质细胞排出修饰的角蛋白可能在体内半抗原敏化过程中发挥作用，应进一步研究。
