Cell Biology, Deutsches Rheuma-Forschungszentrum Berlin (DRFZ), an Institute of the Leibniz Association, 10117 Berlin, Germany.
Klinik und Poliklinik für Allgemein-, Viszeral- und Thoraxchirurgie, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.
Cold Spring Harb Perspect Biol. 2021 Jul 1;13(7):a038083. doi: 10.1101/cshperspect.a038083.
The molecular basis of the persistence of experienced T lymphocytes, also known as "memory T lymphocytes," is still enigmatic. We are beginning to understand their considerable heterogeneity and topographic compartmentalization into memory T cells circulating through the body and those residing in a particular tissue. In some tissues, like murine spleen, subpopulations of memory T cells proliferating in the absence of antigen (homeostatic proliferation) have been described. Other populations are maintained resting in terms of transcription, mobility, and proliferation in dedicated survival niches organized by stromal cells. The survival of these memory T cells is conditional on being in such a niche, where they can persist for a lifetime. Circulating memory T lymphocytes of distinct immune responses slowly decline in numbers over time. The rules governing their entry into and exit from blood, as well as their lifestyle outside of the blood and their relation to resident memory T cells are poorly understood. Homeostasis of circulating, proliferating, and resting memory T cells is obviously controlled by different rheostats: tissue-exit and tissue-entry signals for circulating and proliferation-inducing signals for proliferating memory T cells. For tissue-resident, resting memory T cells, it is the availability of their survival niche. Apparently, this mechanism (i.e., the link between memory T cell and stromal cell) is so robust that it provides efficient T-cell memory over a lifetime in tissues such as the bone marrow.
记忆 T 细胞（也称为“经验性 T 淋巴细胞”）持续存在的分子基础仍然是个谜。我们开始理解它们相当大的异质性和拓扑分区，分为循环于全身的记忆 T 细胞和驻留在特定组织中的记忆 T 细胞。在某些组织中，如鼠脾，已经描述了在没有抗原的情况下增殖的记忆 T 细胞亚群（稳态增殖）。其他群体则以静止状态存在，其转录、迁移和增殖受到基质细胞组成的特定生存龛的调控。这些记忆 T 细胞的存活取决于它们所处的这种龛位，在这种龛位中，它们可以终生存在。不同免疫反应的循环记忆 T 淋巴细胞的数量会随着时间的推移而缓慢减少。控制它们进出血液的规则，以及它们在血液外的生活方式及其与驻留记忆 T 细胞的关系，目前还了解甚少。循环、增殖和静止记忆 T 细胞的稳态显然受到不同变阻器的控制：循环和增殖记忆 T 细胞的组织退出和组织进入信号，以及增殖记忆 T 细胞的增殖诱导信号。对于组织驻留的静止记忆 T 细胞，其生存龛位是可用的。显然，这种机制（即记忆 T 细胞与基质细胞之间的联系）非常强大，它可以在骨髓等组织中提供高效的 T 细胞记忆。
