Virus-specific TRM cells of both donor and recipient origin reside in human kidney transplants

Tissue-resident lymphocytes (TRLs) are critical for local protection against viral pathogens in peripheral tissue. However, it is unclear if TRLs perform a similar role in transplanted organs under chronic immunosuppressed conditions. The present study aimed to characterize the TRL compartment in human kidney transplant nephrectomies and examine its potential role in antiviral immunity. Paired single-cell transcriptome and T-cell receptor (TCR) sequencing showed that donor and recipient tissue-resident memory T (TRM) cells exhibit striking similarities in their transcriptomic profiles and share numerous TCR clonotypes predicted to target viral pathogens. Lymphocytes from kidney transprant nephrectomy specimens were obtained through mechanical and enzymatic (colleganase IV) digestion and the mononuclear cells were harvested through Ficoll density gradient centrifugation. Next, CD4+ and CD8+ tissue-resident memory T (TRM) cells were sorted from these mononuclear cell samples (n=4) using fluorescent-activated cell sorting (FACS). Residency of TRM cells was defined as the co-expression of CD69 plus CD103 and/or CD49a. Sorted TRM cells of the four samples were used for paired single-cell RNA and TCR sequencing using the 10x genomics platform.