Abstract
Tissue-resident memory T (TRM) cells are characterized by their surface expression of CD69 and can be subdivided in CD103+ and CD103- TRM cells. The origin and functional characteristics of TRM cells in the renal allograft are largely unknown. To determine these features we studied TRM cells in transplant nephrectomies. TRM cells with a CD103+ and CD103- phenotype were present in all samples (n = 13) and were mainly CD8+ T cells. Of note, donor-derived TRM cells were only detectable in renal allografts that failed in the first month after transplantation. Grafts, which failed later, mainly contained recipient derived TRM cells. The gene expression profiles of the recipient derived CD8+ TRM cells were studied in more detail and showed a previously described signature of tissue residence within both CD103+ and CD103- TRM cells. All CD8+ TRM cells had strong effector abilities through the production of IFNγ and TNFα, and harboured high levels of intracellular granzyme B and low levels of perforin. In conclusion, our results demonstrate that donor and recipient TRM cells reside in the rejected renal allograft. Over time, the donor-derived TRM cells are replaced by recipient TRM cells which have features that enables these cells to aggressively respond to the allograft.