Organ Transplantation

Caring for the patient with a failing allograft: challenges and opportunities Purpose of review The population of kidney transplant recipients with advanced chronic kidney disease is growing but their outcomes are poor and care is not standardized. There has been wide variety of research in recent years on different aspects of care in failing allografts, and these research findings may help the providers in optimizing care. The purpose of the review is to outline the challenges and opportunities in management of failing allograft, and provide tools for improvement. Recent findings This review summarizes the recent research in field of failing allograft including outcomes, immunosuppression, risk factor management, multidisciplinary CKD care, dialysis initiation, nephrectomy and re-transplantation. Summary Kidney allograft failure is a period of higher risk of mortality compared with other transition periods for patients with ESRD. Risk mitigation is a complex challenge for patients and their care teams. In addition to summarizing the recent literature, we propose a checklist approach to the various issues, medical, surgical, psychological and nutritional as patients approach kidney transplant failure while they consider initiation of dialysis and possible repeat transplantation. Once standard algorithms are instituted, studies can be conducted to identify those high-value interventions that actually reduce morbidity and mortality risk during this transition period. Correspondence to Nikhil Agrawal, Beth Israel Deaconess Medical Center, Boston, MA, 02215, USA. Tel: +617 632 9700; e-mail: nagrawa2@bidmc.harvard.edu Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.

A diagnostic 'C' saw: the Ups and downs of C1q testing Purpose of review The present review will focus on recently published data of solid organ allograft recipients reporting that patients with de-novo donor-specific HLA antibodies (DSA) that fix complement in vitro have a significantly higher risk for antibody-mediated rejection (AMR) and/or graft loss compared to patients whose de-novo DSA do not fix complement or patients who present with preexisting complement fixing DSA. Recent findings HLA DSAs that fix complement in vitro appear to be a key indicator for rejection and failure of kidney, heart, and lung allografts from studies performed around the world. The majority of these studies are population based and retrospective in nature. Although these studies seemingly indicate that in-vitro complement activating DSAs represent a higher clinical risk than noncomplement fixing DSAs, the majority have not accounted for false-negative reactions attributable to the so-called prozone/interference phenomenon. In the limited number of published studies addressing that concern, high mean fluorescence intensity (MFI) value noncomplement fixing DSAs correlate as well as complement fixing DSAs with AMR and graft loss. Combined with the cost of additional testing, these observations bring into question whether there is sufficient clinical applicability to warrant routine testing for complement fixing antibodies. Summary Complement fixing DSAs are clearly associated with AMR and/or loss of transplanted allografts. However, under appropriate testing conditions, complement fixing capability typically correlates with MFI values of the DSAs. As such, the routine implementation of in-vitro assays to determine whether DSAs fix complement is of questionable value especially when considering additional issues such as cost of testing, logistics, and whether the test results factor into individualized patient care. Correspondence to Howard M. Gebel, PhD, Department of Pathology, Room HB53, 1364 Clifton Road NE, Atlanta, GA 30322, USA. Tel: +404 712 8199; fax: +404 712 4717; e-mail: hgebel@emory.edu Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.

Epitope matching in kidney transplantation: recent advances and current limitations Purpose of review Evolution of human leukocyte antigen (HLA) molecular typing techniques has progressively enabled more accurate determination of the three-dimensional building blocks that form the antibody accessibility and binding sites of each HLA allele. These immunogenic HLA regions known as epitopes are composed of polymorphic sequences of amino acid residues termed eplets. This review provides a critical appraisal of the current understanding of epitope compatibility in kidney transplantation. Recent findings There is a tendency to suggest that epitope matching is likely to be superior to broad antigen HLA matching such that the allocation of donor kidneys to patients with a more favorable epitope compatibility profile may lead to better allograft outcomes. A growing body of work has highlighted the association between a greater number of eplet mismatches and adverse allograft outcomes, and approaches using eplet matching have been successfully implemented in organ allocation programs. However, our understanding of epitope compatibility remains in its infancy, requiring further and more in-depth evaluation. Critically, it remains unclear how best to translate findings derived at the population level to the care of individual patients. Questions that need to be answered include a lack of consensus in the definition and interpretation of epitope compatibility, are class I and II compatibility of similar clinical importance, how best to define predetermined mismatch thresholds for utilization in organ allocation, and whether other properties such as differences in electrostatic potential between donor and recipient HLA alleles are also important in determining immunological compatibility. Summary Epitope matching likely represents a valid progression in understanding donor–recipient HLA compatibility. However, more clinical data and a better understanding about differences in methods to determine epitope compatibility are required before the approach can be widely applied in clinical practice. Corresponding to Nicholas G. Larkins, MBBS (Hons), FRACP MMed (Clin Epi), PhD, Department of Nephrology, Perth Children's Hospital, 15 Hospital Ave., Nedlands, Perth, Western Australia 6009, Australia. Tel: +61 08 6456 0216; e-mail: nicholas.larkins@health.wa.gov.au Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Website (www.co-transplantation.com). Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.

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