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。

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, USA
2 Emory Vaccine Center, Emory University School of Medicine, and,
3 Department of Biology, Emory University, Atlanta, Georgia 30322, USA
4 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.