Kyburz D, Speiser D E, Battegay M, Hengartner H, Zinkernagel R M
Kantonsspital Bruderholz, Basel, Switzerland.
Eur J Immunol. 1993 Jul;23(7):1540-5. doi: 10.1002/eji.1830230722.
Immunocompetent adult mice infected with lymphocytic choriomeningitis virus (LCMV) generate a strong antiviral cytotoxic T cell response that clears virus from all organs. Although there is good evidence that immune cytotoxic T lymphocytes (CTL) kill target cells in vitro, in vivo it is debated whether antiviral activity of CD8+ T cells is mediated via direct target cell lysis or via soluble mediators. To demonstrate CD8+ T cell-mediated destruction of infected cells in vivo a specific cell-internal releasable marker was used as label, i.e. the nucleoprotein (NP) of LCMV. Since LCMV is non-cytopathic the viral NP will only be released in substantial amounts because of destruction of infected host cells by immune CTL. It is shown here that the amount of NP released from infected and 51Cr-labeled target cells in vitro correlated well with the amount of radioactivity released. Viral NP released in vivo by CTL is bound and masked by the anti-NP antibodies that are produced very early and efficiently. However, NP could readily be detected in sera of LCMV-infected CD8+ competent mice that could not generate antibodies specific for the NP because they were treated with a depleting anti-CD4 antibody. NP was also detected in the cerebrospinal fluid of mice suffering from CD8+ T cell-mediated lymphocytic choriomeningitis after intracerebral infection. NP titers in sera of anti-CD4-treated LCMV-infected mice exhibited a peak around day 7-8 when CTL activity was highest. When mice were CD8 T cell-depleted with anti-CD8 monoclonal antibody or in LCMV-carrier mice, no NP was detected in the serum. Highly activated LCMV-specific CTL adoptively transfused to LCMV-infected irradiated recipient mice also caused a time-dependent release of NP into serum. This confirms that the CD8+ population is responsible for the release of NP from infected host cells. These results represent an in vivo correlate of CTL-mediated cytolysis and evidence that antiviral cytotoxic T cells are cytolytic in vivo. They also suggest that antibody responses to internal antigens of non-cytopathic viruses may signal CD8+ T cell-mediated destruction of infected host cells.
感染淋巴细胞性脉络丛脑膜炎病毒（LCMV）的免疫功能正常的成年小鼠会产生强烈的抗病毒细胞毒性T细胞反应，从而清除所有器官中的病毒。尽管有充分证据表明免疫细胞毒性T淋巴细胞（CTL）在体外可杀死靶细胞，但在体内，CD8 + T细胞的抗病毒活性是通过直接靶细胞裂解还是通过可溶性介质介导仍存在争议。为了证明体内CD8 + T细胞介导的感染细胞破坏，使用了一种特定的细胞内可释放标记物作为标记，即LCMV的核蛋白（NP）。由于LCMV是非细胞病变性的，病毒NP只会因免疫CTL对感染宿主细胞的破坏而大量释放。此处显示，体外从感染并经51Cr标记的靶细胞释放的NP量与释放的放射性量密切相关。CTL在体内释放的病毒NP会被很早就高效产生的抗NP抗体结合并掩盖。然而，在感染LCMV的CD8 +功能正常的小鼠血清中很容易检测到NP，这些小鼠由于用耗竭性抗CD4抗体处理而无法产生针对NP的特异性抗体。在脑内感染后患有CD8 + T细胞介导的淋巴细胞性脉络丛脑膜炎的小鼠脑脊液中也检测到了NP。抗CD4处理的LCMV感染小鼠血清中的NP滴度在CTL活性最高的第7 - 8天左右出现峰值。当用抗CD8单克隆抗体使小鼠的CD8 T细胞耗竭时或在LCMV携带小鼠中，血清中未检测到NP。将高度活化的LCMV特异性CTL过继转移到受LCMV感染的经辐照受体小鼠中，也会导致NP随时间依赖性释放到血清中。这证实了CD8 +群体负责从感染的宿主细胞中释放NP。这些结果代表了CTL介导的细胞溶解在体内的相关性，并证明抗病毒细胞毒性T细胞在体内具有细胞溶解性。它们还表明，对非细胞病变性病毒内部抗原的抗体反应可能标志着CD8 + T细胞介导的感染宿主细胞破坏。
