Pre-transplant T-cell clonal analysis identifies CD8 donor reactive clones that contribute to kidney transplant rejection.

Introduction: Responses to allogeneic human leukocyte antigen (HLA) molecules limit the survival of transplanted organs. The changes in T-cell alloreactivity that contribute to this process, however, are not fully understood. We defined a set of donor reactive T-cell clones (DRTC) with the goal to elucidate signatures of kidney allograft rejection.

Methods: DRTC were identified pretransplant using an anti-donor mixed lymphocyte reaction assay: CFSE-diluting CD4 and CD8 DRTC were flow-sorted, and the TCR sequences were identified using Adaptive Immunosequencing. DRTC were then tracked in post-transplant biopsies, blood, and urine samples in a cohort of kidney transplant recipients.

Results: In patients with an abnormal biopsy, the majority of CD8 DRTC found within the allograft were detected in the circulating pre-transplant repertoire. Circulating CD8 DRTC were more abundant pre- and post-transplant in patients that received non-lymphodepletional induction and developed an abnormal biopsy when compared to stable patients. Additionally, DRTC were detected as early as two weeks post-transplant in the urine of some patients, with some of these clones subsequently identified in follow-up kidney biopsy samples.

Discussion: The findings of our study add to our understanding of T-cell alloreactivity following kidney transplantation and provide evidence for the role of pre-defined alloreactive T-cells in the development of allograft rejection.