Deep Phenotyping of the Renal Allograft to Prognosticate Clinical Outcomes

The goal of this observational study is to determine phenotypic, transcriptional, and epigenetic underpinnings of renal allograft rejection in renal transplant rejection. The main questions it aims to answer are:

* To determine the phenotype, frequency, location, and the inter-cellular interactions between the cells that constitute intra-graft inflammatory infiltrate in acute ejection. * To determine the phenotype, frequency, location, and the inter-cellular interactions between the cells that constitute intra-graft inflammatory infiltrate in recurrent/recalcitrant rejection vs. rejection that resolves with therapy. * To generate a scRNA sequencing (scRNAseq) map of the intra-graft immune cells and the renal parenchymal cells and compare the transcriptional and epigenetic changes within these cells in recurrent/recalcitrant rejection vs. rejection that resolves with therapy. * To determine phenotypic changes associated with chronic rejection.

Participants will be asked to provide the following research specimens:

* Renal biopsy specimens at the following timepoints: day of transplantation (pre-implantation and post-perfusion); routine protocol biopsies at 3 months and 12 months; and clinically indicated for-cause biopsies at any timepoint from time-0 to 1-yr post-transplantation. The 1st research core will be used for routine histopathological examination and left over tissue from this core will be used for deep phenotyping using multiparameter immunophenotyping, and digital spatial profiling. The second research core will be used for extraction of cells and nuclei for scRNAseq and snATACseq. * Blood samples will be processed to obtain plasma (for cytokine, chemokine and DSA measurements) and PBMC (for deep phenotyping and molecular analyses). For each collection timepoint, up to 75 mL (about 5 tablespoons) will be collected. * Prospective clinical data and outcomes will be collected from participant medical records. * Follow-Up Period: For-cause biopsies from 1-yr to 5-yr post-transplantation (by the transplant nephrologist): no additional cores will be obtained for research from these biopsies. The left-over tissue from the clinically indicated biopsy cores will be analyzed by deep phenotyping and digital spatial profiling. Blood samples will be processed to obtain plasma (for cytokine, chemokine and DSA measurements) and PBMC (for deep phenotyping and molecular analyses).