Fig. 1 |. Effects of secondary infection on a pre-existing T_RM cell population.

CD8⁺ T_RM cells (green) are motile sentinels that patrol and survey their tissue microenvironments for reinfection. When they recognize their target antigen (Ag) during reinfection, CD8⁺ T_RM cells arrest and undergo in situ proliferation to generate a secondary pool of T_RM cells that does not exit into the circulation. Antigen-specific (purple) and bystander (blue) CD8⁺ T_CIRC cells are also recruited into the infected tissue and adopt long-term tissue residency without displacing the pre-existing T_RM cells, thereby increasing the number and repertoire of T_RM cells in the tissue. Credit: Marina Spence/Springer Nature