Successful kidney transplantation across a positive complement-dependent cytotoxicity crossmatch by using C1q assay-directed, bortezomib-assisted desensitization: A case report

Kidney transplantation in highly sensitized recipients

In kidney transplantation (KT), overcoming donor shortage is particularly challenging in patients with preexisting donor-specific antibodies (DSAs) against human leukocyte antigen (HLA), called HLA-incompatible KT (HLAi KT), carrying the risk of rejection and allograft loss. Thus, it is necessary to accurately evaluate the degree of sensitization before HLAi KT, and undertake appropriate pretreatment strategies. To determine the degree of sensitization, complement-dependent cytotoxicity has been the only method employed; the development of a method using flow cytometry further improved the test sensitivity. However, these tests present disadvantages, including the need for living cells, with a solid-phase assay developed to resolve this problem. Currently, the method using Luminex (Luminex Corp.) is widely used in clinical practice. As this method measures DSAs using single antigen beads, it is possible to classify immunological risks by measuring the type and amount of DSAs. Furthermore, there have been major advances in methods that involve DSA removal before HLAi KT. In the early stages of desensitization, plasmapheresis and intravenous immunoglobulins were the main treatment methods employed; however, the introduction of CD20 monoclonal antibody and proteasome inhibitors further increased the success rate of desensitization. Currently, HLAi KT has been established as an important transplant method, but an understanding of DSAs and a novel desensitization treatment are warranted.

Evaluation of three different laboratory methods to detect preformed human leukocyte antigen antibodies in a South African kidney transplant population

Background

Anti-human leukocyte antigen antibodies (anti-HLA) play a crucial role in graft. Detection of anti-HLA, both pre- and post-transplant is a crucial investigation in clinical organ transplantation.

Objectives

Three methodologies for the detection of lymphocytotoxic antibodies were compared to establish which of these is best suited to optimise pre-transplant donor-recipient matching.

Methods

Serum samples from 15 renal transplant patients were tested for the presence of anti-HLA by i) cytotoxic-dependent cross-match (CDCXM), ii) flow cytometric cross-match (FCXM) and iii) Luminex-based donor specific antibody cross-match (DSAXM) method, Confirmatory tests for the presence of preformed HLA antibodies were tested using Luminex methodology.

Results

Two (13%) of the 15 patients had positive HLA Class I antibodies (Ab) using all 3 methods. An additional 2 HLA Class I Ab were identified with FCXM/CDCXM. DSAXM identified 1 HLA Class I positive, not indicated by CDCXM/FCXM.

High HLA Class II positivity (40%), identified by CDCXM, while DSAXM and FCXM identified two and one patients, respectively. CDCXM produced 4 false-positive results confirmed by lymphocyte single antigen (LSA) assay.

Conclusions

The DSAXM method appears to add value in pre-transplantation screening to identify pre-sensitised patients that may not reject the donor graft due to the absence of donor-specific antibodies.

Recent Innovations in Kidney Transplants

Current donor pool utilization is unable to meet the high demand for kidney transplants. Donor pool expansion using expanded-criteria donors and dual kidney transplantation are viable options. Advances in diagnosing antibody-mediated rejection and targeting immunosuppression increase long-term transplantation success. Further exploration of minimally invasive surgical techniques, kidney bioengineering, and artificial-implantable renal devices hold promise for the future.