Gutsy memory T cells stand their ground against pathogens.

Elegant fate-mapping models to label intestinal tissue-resident memory CD8 + T (T RM ) cells demonstrate retention and lack of expansion of CD103 + T RM cells, whereas intestinal CD103 - memory cells expand, forming both new tissue-localized CD103 + and CD103 - T RM cells (see related Research Articles by Fung et al. and von Hoesslin et al. ).