Allo-reactive tissue-resident T cells causing damage: An inside job.

Tissue-resident memory T cells (TRM cells) reside in the epithelium and contribute to the first line defense against invading pathogens. Snyder et al. (2022. J. Exp. Med.https://doi.org/10.1084/jem.20212059) now report that clonally expanded, recipient T cells persist as TRM cells in human lung allografts despite intensive immunosuppression. Their persistence may contribute to chronic allograft dysfunction.