Micheletti F, Guerrini R, Formentin A, Canella A, Marastoni M, Bazzaro M, Tomatis R, Traniello S, Gavioli R
Department of Biochemistry and Molecular Biology, University of Ferrara, Ferrara, Italy.
Eur J Immunol. 1999 Aug;29(8):2579-89. doi: 10.1002/(SICI)1521-4141(199908)29:08<2579::AID-IMMU2579>3.0.CO;2-E.
The latent membrane protein 2 is an immunogenic antigen expressed in Epstein-Barr virus (EBV)-associated tumors and consequently it may represent a target for specific cytotoxic T lymphocyte (CTL)-based immunotherapies. However, the efficacy of such a therapy is limited by the poor immunogenicity of the protein that induces weak CTL responses directed to the CLGGLLTMV (CLG) epitope only in the minority of EBV-seropositive donors. We have now demonstrated that selective peptide stimulation of peripheral blood lymphocytes induced CLG-specific CTL in all donors, suggesting that this epitope can be a suitable target for specific immunotherapies. We found that the CLG peptide has a low affinity for HLA-A0201 and does not produce stable complexes, both factors that are likely to determine the strength of CTL responses to this epitope. Therefore, we synthesized and tested CLG analogues carrying single or combined amino acid substitutions to increase HLA/peptide stability. Among the analogues tested we identified two peptides which, compared to the natural epitope, showed higher affinity for HLA-A0201 molecules, and produced stable complexes. These peptides demonstrated a potent, specific stimulatory capacity and could be used for selective CTL-based therapies.
潜伏膜蛋白2是一种在爱泼斯坦-巴尔病毒（EBV）相关肿瘤中表达的免疫原性抗原，因此它可能成为基于特异性细胞毒性T淋巴细胞（CTL）的免疫疗法的靶点。然而，这种疗法的疗效受到该蛋白免疫原性较差的限制，该蛋白仅在少数EBV血清阳性供体中诱导针对CLGGLLTMV（CLG）表位的微弱CTL反应。我们现在已经证明，对外周血淋巴细胞进行选择性肽刺激可在所有供体中诱导出CLG特异性CTL，这表明该表位可能是特异性免疫疗法的合适靶点。我们发现CLG肽对HLA-A0201的亲和力较低，且不会产生稳定的复合物，这两个因素可能决定了CTL对该表位反应的强度。因此，我们合成并测试了携带单个或组合氨基酸取代的CLG类似物，以提高HLA/肽的稳定性。在测试的类似物中，我们鉴定出两种肽，与天然表位相比，它们对HLA-A0201分子具有更高的亲和力，并产生稳定的复合物。这些肽表现出强大的、特异性的刺激能力，可用于基于CTL的选择性疗法。
