Nature：哺乳动物宿主CD8+ T细胞数量的适应性变化

反复暴露于病原体及以杀死病原体为使命的记忆性CD8+ T-细胞的生成，被认为会导致事先存在的记忆性T-细胞存量的消耗，以保持记忆腔的总体大小不变。但用小鼠进行的新的研究工作表明，记忆性CD8+ T-细胞腔的大小在免疫之后会增加，而且新的记忆性CD8+ T-细胞的生成并不会显著减少事先存在的记忆性CD8+ T-细胞的数量。关于哺乳动物宿主CD8+ T-细胞数量能根据免疫经验发生适应性变化的发现，对于疫苗的生产可能具有重要意义，因为我们也许有可能大量引入特异性CD8+ T-细胞，而不会影响以前就有的、针对其他感染的免疫能力。（生物谷Bioon.com）
生物谷推荐原始出处：
Nature 457, 196-199 (8 January 2009) doi:10.1038/nature07486
Memory CD8 T-cell compartment grows in size with immunological experience
Vaiva Vezys1,2,4, Andrew Yates3,4, Kerry A. Casey1, Gibson Lanier2, Rafi Ahmed2, Rustom Antia3 & David Masopust1,2
1 Department of Microbiology and Center for Immunology, University of Minnesota, Minneapolis, Minnesota 55455, USA2 Emory Vaccine Center, Emory University School of Medicine, and,3 Department of Biology, Emory University, Atlanta, Georgia 30322, USA4 These authors contributed equally to this work.
Memory CD8 T cells, generated by natural pathogen exposure or intentional vaccination, protect the host against specific viral infections1. It has long been proposed that the number of memory CD8 T cells in the host is inflexible, and that individual cells are constantly competing for limited space2, 3. Consequently, vaccines that introduce over-abundant quantities of memory CD8 T cells specific for an agent of interest could have catastrophic consequences for the host by displacing memory CD8 T cells specific for all previous infections4, 5, 6. To test this paradigm, we developed a vaccination regimen in mice that introduced as many new long-lived memory CD8 T cells specific for a single vaccine antigen as there were memory CD8 T cells in the host before vaccination. Here we show that, in contrast to expectations, the size of the memory CD8 T-cell compartment doubled to accommodate these new cells, a change due solely to the addition of effector memory CD8 T cells. This increase did not affect the number of CD4 T cells, B cells or naive CD8 T cells, and pre-existing memory CD8 T cells specific for a previously encountered infection were largely preserved. Thus, the number of effector memory CD8 T cells in the mammalian host adapts according to immunological experience. Developing vaccines that abundantly introduce new memory CD8 T cells should not necessarily ablate pre-existing immunity to other infections.