Although tissue-resident memory T cells (T_RM cells) are critical in fighting infection, their fate after local pathogen re-encounter is unknown. Here we found that skin T_RM cells engaged virus-infected cells, proliferated in situ in response to local antigen encounter and did not migrate out of the epidermis, where they exclusively reside. As a consequence, secondary T_RM cells formed from pre-existing T_RM cells, as well as from precursors recruited from the circulation. Newly recruited antigen-specific or bystander T_RM cells were generated in the skin without displacement of the pre-existing T_RM cell pool. Thus, pre-existing skin T_RM cell populations are not displaced after subsequent infections, which enables multiple T_RM cell specificities to be stably maintained within the tissue.

中文翻译：

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抗病毒召回反应后，局部增殖可维持稳定的组织驻留记忆T细胞库。

尽管组织驻留性记忆T细胞（T _RM细胞）在抵抗感染方面至关重要，但在局部病原体再次遭遇后它们的命运尚不清楚。在这里，我们发现皮肤T _RM细胞参与了病毒感染的细胞，响应于局部抗原的接触而原位增殖，并且没有迁移出表皮，而表皮只是它们所在的位置。结果，由先前存在的T _RM细胞以及从循环中募集的前体形成了次级T _RM细胞。在皮肤中产生了新募集的抗原特异性或旁观者T _RM细胞，而不会取代现有的T _RM细胞池。因此，先前存在的皮肤T _RM在随后的感染后，细胞群不会被置换，这使得多种_TRM细胞特异性能够在组织内稳定地保持。