Lukacher A E, Moser J M, Hadley A, Altman J D
Department of Pathology, Emory Vaccine Center, Emory University School of Medicine, Atlanta, GA 30322, USA.
J Immunol. 1999 Sep 15;163(6):3369-78.
T cells are critical for clearing infection and preventing tumors induced by polyoma virus, a natural murine papovavirus. We previously identified the immunodominant epitope for polyoma virus-specific CTL in tumor-resistant H-2k mice as the Dk-restricted peptide, MT389-397, derived from the polyoma middle T oncoprotein. In this study, we developed tetrameric Dk complexes containing the MT389-397 peptide to directly visualize and enumerate MT389-397-specific CTL during polyoma virus infection. We found that Dk/MT389 tetramer+CD8+ T cells undergo a massive expansion during primary infection such that by day 7 postinfection these Ag-specific CD8+ T cells constitute approximately 20% of the total and approximately 40% of the activated CD8+ T cells in the spleen. This expansion of Dk/MT389 tetramer+CD8+ T cells parallels the emergence of MT389-397-specific ex vivo cytolytic activity and clearance of polyoma virus. Notably, Dk/MT389 tetramer+CD8+ T cells are maintained in memory at very high levels. The frequencies of Dk/MT389 tetramer+CD8+ effector and memory T cells in vivo match those of CD8+ T cells producing intracellular IFN-gamma after 6-h in vitro stimulation by MT389-397 peptide. Consistent with preferential Vbeta6 expression by MT389-397-specific CD8+CTL lines and clones, Dk/MT389 tetramer+CD8+ T cells exhibit biased expression of this Vbeta gene segment. Finally, we show that Dk/MT389 tetramer+CD8+ T cells efficiently infiltrate a polyoma tumor challenge to virus-immune mice. Taken together, these findings strongly implicate virus-induced MT389-397-specific CD8+ T cells as essential effectors in eliminating polyoma-infected and polyoma-transformed cells in vivo.
T细胞对于清除由多瘤病毒（一种天然的鼠乳头瘤病毒）引起的感染和预防肿瘤至关重要。我们之前在肿瘤抗性H-2k小鼠中鉴定出多瘤病毒特异性CTL的免疫显性表位为源自多瘤病毒中T癌蛋白的Dk限制性肽MT389-397。在本研究中，我们开发了包含MT389-397肽的四聚体Dk复合物，以在多瘤病毒感染期间直接可视化并计数MT389-397特异性CTL。我们发现，Dk/MT389四聚体+CD8+T细胞在初次感染期间会大量扩增，以至于在感染后第7天，这些抗原特异性CD8+T细胞在脾脏中占总CD8+T细胞的约20%，占活化CD8+T细胞的约40%。Dk/MT389四聚体+CD8+T细胞的这种扩增与MT389-397特异性体外细胞溶解活性的出现以及多瘤病毒的清除相平行。值得注意的是，Dk/MT389四聚体+CD8+T细胞以非常高的水平维持在记忆状态。体内Dk/MT389四聚体+CD8+效应细胞和记忆T细胞的频率与在体外经MT389-397肽刺激6小时后产生细胞内IFN-γ的CD8+T细胞的频率相匹配。与MT389-397特异性CD8+CTL系和克隆优先表达Vbeta6一致，Dk/MT389四聚体+CD8+T细胞表现出该Vbeta基因片段的偏向性表达。最后，我们表明Dk/MT389四聚体+CD8+T细胞能有效浸润病毒免疫小鼠的多瘤肿瘤攻击部位。综上所述，这些发现有力地表明病毒诱导的MT389-397特异性CD8+T细胞是体内清除多瘤病毒感染和多瘤病毒转化细胞的重要效应细胞。
