AUTHOR=Stein Jens V. , Ruef Nora , Wissmann Stefanie 

TITLE=Organ-Specific Surveillance and Long-Term Residency Strategies Adapted by Tissue-Resident Memory CD8+ T Cells

JOURNAL=Frontiers in Immunology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2021.626019

DOI=10.3389/fimmu.2021.626019

ISSN=1664-3224

ABSTRACT=<p>Tissue-resident CD8<sup>+</sup> T cells (CD8<sup>+</sup> T<sub>RM</sub>) populate lymphoid and non-lymphoid tissues after infections as first line of defense against re-emerging pathogens. To achieve host protection, CD8<sup>+</sup> T<sub>RM</sub> have developed surveillance strategies that combine dynamic interrogation of pMHC complexes on local stromal and hematopoietic cells with long-term residency. Factors mediating CD8<sup>+</sup> T<sub>RM</sub> residency include CD69, a surface receptor opposing the egress-promoting S1P1, CD49a, a collagen-binding integrin, and CD103, which binds E-cadherin on epithelial cells. Moreover, the topography of the tissues of residency may influence T<sub>RM</sub> retention and surveillance strategies. Here, we provide a brief summary of these factors to examine how CD8<sup>+</sup> T<sub>RM</sub> reconcile constant migratory behavior with their long-term commitment to local microenvironments, with a focus on epithelial barrier organs and exocrine glands with mixed connective—epithelial tissue composition.</p>