Direct sequence identification and kinetic analysis of an MHC class I-restricted Listeria monocytogenes CTL epitope.
Direct sequence identification and kinetic analysis of an MHC class I-restricted Listeria monocytogenes CTL epitope.
复制标题
MHC I 类限制性单核细胞增生李斯特菌 CTL 表位的直接序列鉴定和动力学分析。
作者：
Eric G. Pamer
小鼠感染胞内细菌单核细胞增生李斯特菌后，可产生对多种细菌肽具有特异性的MHC I类限制性CTL。与MHC分子结合的自身肽的种类和相对丰度使得病原体衍生肽的鉴定变得困难。在这份报告中，病原体衍生的CTL表位的序列是通过直接分析从MHC I类分子中提取的肽来确定的。p60 217-225抗原表位被提呈给L.单核细胞生成素特异性CTL通过H-2Kd MHC I类分子产生，并且来源于p60，一种分泌的侵袭相关蛋白。感染细胞中p60 217-225的定量显示，该表位在感染2小时内可检测到，并且在9小时感染后，每个感染细胞有超过3000个表位。这与另一种主要的L.单核细胞增多性表位，其以低于200个表位/细胞的量存在，直到感染5小时，并且在感染后9小时达到800个表位/细胞。这份报告表明，通过直接序列分析从MHC分子分离的肽来鉴定新的T淋巴细胞表位是可行的。此外，感染细胞中T细胞表位的动力学和定量分析是研究对复杂细胞内病原体的多特异性CTL反应的有用方法。
Murine infection with the intracellular bacterium Listeria monocytogenes elicits MHC class I-restricted CTL with specificity for multiple bacterial peptides. The variety and relative abundance of self-peptides bound by MHC molecules make identification of pathogen-derived peptides difficult. In this report, the sequence of a pathogen-derived CTL epitope is determined by direct analysis of peptides extracted from MHC class I molecules. The epitope, p60 217-225, is presented to L. monocytogenes-specific CTL by the H-2Kd MHC class I molecule and is derived from p60, a secreted invasion-associated protein. Quantitation of p60 217-225 in infected cells shows that this epitope is detectable within 2 h of infection and, after a 9-h infection, there are over 3000 epitopes per infected cell. This contrasts with listeriolysin 91-99, the other major L. monocytogenes epitope, which is present in quantities below 200 epitopes per cell until 5 h of infection and reaches 800 epitopes per cell 9 h after infection. This report shows that identifying new T lymphocyte epitopes by direct sequence analysis of peptides isolated from MHC molecules is feasible. Furthermore, kinetic and quantitative analysis of T cell epitopes in infected cells is a useful approach to investigate the multispecific CTL response to complex intracellular pathogens.