Donor HLA genotyping of ex vivo expanded urine cells from kidney transplant recipients

Abstract

Antibody-mediated rejection (AMR) induced by donor-specific anti-HLA antibodies (DSA) remains a major cause of long-term graft loss after kidney transplantation. Currently, the presence of DSA cannot always be determined at a specific allele level, because existing donor HLA typing is low resolution and often incomplete, lacking HLA-DP, and occasionally HLA-C and HLA-DQ information and historical donor DNA samples are not available for HLA retyping. Here we present a novel, non-invasive technique for obtaining donor DNA from selectively expanded donor cells from urine of renal transplant recipients. Urine-derived cells were successfully expanded ex vivo from 31 of 32 enrolled renal transplant recipients, and with DNA obtained from these cells, donor HLA typing was unambiguously determined for HLA-A, -B, -C, -DRB1, -DQA1, -DQB1, -DPA1 and -DPB1 loci by next-generation sequencing.Our results showed 100% concordance of HLA typing data between donor peripheral blood and recipient urine-derived cells. In comparison, HLA typing showed that DNA derived from urine sediments mainly contained recipientderived DNA. We also present the successful application of our novel technique in a clinical case of AMR in a renal transplant recipient. Urine-derived donor cells can be isolated from kidney transplant recipients and serve as a suitable source of donor material for reliable high-resolution HLA genotyping.Thus, this approach can aid the assessment of DSA specificity to support the diagnosis of AMR as well as the evaluation of treatment efficacy in kidney transplant recipients when complete donor HLA information and donor DNA are unavailable.

Extended genomic HLA typing identifies previously unrecognized mismatches in living kidney transplantation

“…Though it would not yet influence the allocation process itself, the results can still help to improve donorspecific antibody recognition and to provide a more personalized transplant management (44). In this regard, novel methods like DNA extraction from urinary cells are promising approaches for enabling HLA retyping even when donor DNA samples not available (45). In patients who are under evaluation of re-transplantation after graft failure, knowledge of the MM count is also helpful, as it has been shown that the number of panel reactive antibodies increases with each MM (46).…”