Minev B R, Chavez F L, Dudouet B M, Mitchell M S
University of California-San Diego, Cancer Center, La Jolla 92093-0060, USA.
Eur J Immunol. 2000 Aug;30(8):2115-24. doi: 10.1002/1521-4141(2000)30:8<2115::AID-IMMU2115>3.0.CO;2-J.
Cytotoxic T lymphocytes (CTL) recognize minimal peptides of eight to ten residues which are the products of intracellularly processed proteins and are presented at the cell surface by MHC class I molecules. An important step in this process is the translocation of processed proteins from the cytosol across the endoplasmic reticulum membrane mediated by transporter associated with antigen processing (TAP) proteins, or as an alternative, by endoplasmic reticulum insertion signal sequences. We report here that the addition of synthetic signal sequences at the N terminus, but not at the C terminus, of an epitope from the human melanoma antigen MART-1 greatly enhances its presentation in both TAP-deficient and TAP-expressing cells. A newly designed peptide construct, composed of the epitope replacing the hydrophobic part of a natural signal sequence, was also very effective. Interestingly, an artificial signal sequence containing the same epitope was the most efficient construct for enhancing its presentation. These peptide constructs facilitated epitope presentation when loaded into the cytosol of TAP-deficient T2 cells, TAP-expressing melanoma cells and human dendritic cells. These findings may be of practical significance for the development of synthetic anti-cancer vaccines and in vitro immunization of CTL for adoptive immunotherapy.
细胞毒性T淋巴细胞（CTL）识别由细胞内加工的蛋白质产生的8至10个残基的最小肽段，这些肽段由MHC I类分子呈递于细胞表面。这一过程中的一个重要步骤是，加工后的蛋白质通过与抗原加工相关的转运体（TAP）蛋白介导，或者作为一种替代方式，通过内质网插入信号序列，从胞质溶胶转运至内质网膜。我们在此报告，在人黑素瘤抗原MART-1的一个表位的N端而非C端添加合成信号序列，可极大增强其在TAP缺陷细胞和TAP表达细胞中的呈递。一种新设计的肽构建体，由该表位取代天然信号序列的疏水部分组成，也非常有效。有趣的是，包含相同表位的人工信号序列是增强其呈递的最有效构建体。当这些肽构建体被加载到TAP缺陷的T2细胞、TAP表达的黑素瘤细胞和人树突状细胞的胞质溶胶中时，它们促进了表位的呈递。这些发现对于合成抗癌疫苗的开发以及用于过继性免疫治疗的CTL的体外免疫可能具有实际意义。
