Successful renal transplantation despite low levels of donor-specific HLA class I antibody without IVIg or plasmapheresis

Translational research in kidney transplantation and the role of patient engagement

Background

Translational research is an evolving discipline that is intended to bridge the gaps between basic science research, clinical research, and implementation in clinical practice. It is a fluid, multidirectional process that requires strong interdisciplinary collaboration to produce research that is relevant to end-users.

Purpose of this review

This review summarizes current perspectives on translational research and outlines its relevance and importance to kidney transplantation research.

Sources of information

Sources of information used for this review include published reports, articles, and research funding websites.

Findings

Tissue typing is used as an in-depth example of how translational research has been applied in the field of kidney transplant medicine, and how it has resulted in successful implementation of diagnostic and management options for sensitized individuals undergoing kidney transplantation. The value of actively involving kidney transplant stakeholders (patients, caregivers, and clinicians) in setting research priorities and determining relevant outcomes for future investigation is also discussed.

Limitations

This is a narrative review of the literature which has been partly influenced by the perspectives and experiences of its authors.

Implications

Translational and patient-oriented research practices should be incorporated into future research endeavours in the field of kidney transplantation in order to create beneficial change in clinical practice and improve patient outcomes.

What was known before

Translational research which engages patients in the investigative process can enhance the likelihood that medical discoveries will have a meaningful impact at the bedside.

What this adds

This article applies current perspectives on translational research and patient engagement to the field of kidney transplantation, illustrating how these approaches have led to significant advancements in the field. It provides further justification for deliberate, targeted efforts to cross-collaborate and incorporate the patient voice into kidney transplant research.

Poor kidney allograft survival associated with positive B cell - Only flow cytometry cross matches: a ten year single center study

The presence of donor specific antibody (DSA) to class 1 or class 2 HLA as detected respectively in T cell or B cell - only flow cytometry cross matches (FCXMs) are risk factors for renal allograft survival, though the comparative risk of these XMs has not been definitively established. Allograft survival and FCXM data in 624 microcytotoxicity (CDC) XM negative kidney transplants were evaluated. Short and long term allograft survival was significantly less in recipients with T(-) B(+) FCXMs (1 year, 74%, 10 year, 58%) compared to T(+) B(+) FCXMs (1 year, 84%, 10 year, 68%) and to T(-) B(-) FCXM (1 year, 90%, 10 year, 85%). Risk factors were positive FCXM, deceased donor (DD) transplantation and donor age, but not race, gender, recipient age or previous transplant. Recipients with T(-) B(+) and T(+) B(+) FCXMs were at 4.5 and 2.5 fold greater risk, respectively, of DD allograft failure compared to patients with T(-) B(-) FCXMs. The quantitative value of FCXM did not correlate with the duration of graft survival. We conclude that patients with DSA to class 2 HLA have a greater risk of early and late allograft failure compared to patients with DSA to class 1 HLA.

Consensus guidelines on the testing and clinical management issues associated with HLA and non-HLA antibodies in transplantation

BACKGROUND

The introduction of solid-phase immunoassay (SPI) technology for the detection and characterization of human leukocyte antigen (HLA) antibodies in transplantation while providing greater sensitivity than was obtainable by complement-dependent lymphocytotoxicity (CDC) assays has resulted in a new paradigm with respect to the interpretation of donor-specific antibodies (DSA). Although the SPI assay performed on the Luminex instrument (hereafter referred to as the Luminex assay), in particular, has permitted the detection of antibodies not detectable by CDC, the clinical significance of these antibodies is incompletely understood. Nevertheless, the detection of these antibodies has led to changes in the clinical management of sensitized patients. In addition, SPI testing raises technical issues that require resolution and careful consideration when interpreting antibody results.

METHODS

With this background, The Transplantation Society convened a group of laboratory and clinical experts in the field of transplantation to prepare a consensus report and make recommendations on the use of this new technology based on both published evidence and expert opinion. Three working groups were formed to address (a) the technical issues with respect to the use of this technology, (b) the interpretation of pretransplantation antibody testing in the context of various clinical settings and organ transplant types (kidney, heart, lung, liver, pancreas, intestinal, and islet cells), and (c) the application of antibody testing in the posttransplantation setting. The three groups were established in November 2011 and convened for a "Consensus Conference on Antibodies in Transplantation" in Rome, Italy, in May 2012. The deliberations of the three groups meeting independently and then together are the bases for this report.

RESULTS

A comprehensive list of recommendations was prepared by each group. A summary of the key recommendations follows. Technical Group: (a) SPI must be used for the detection of pretransplantation HLA antibodies in solid organ transplant recipients and, in particular, the use of the single-antigen bead assay to detect antibodies to HLA loci, such as Cw, DQA, DPA, and DPB, which are not readily detected by other methods. (b) The use of SPI for antibody detection should be supplemented with cell-based assays to examine the correlations between the two types of assays and to establish the likelihood of a positive crossmatch (XM). (c) There must be an awareness of the technical factors that can influence the results and their clinical interpretation when using the Luminex bead technology, such as variation in antigen density and the presence of denatured antigen on the beads. Pretransplantation Group: (a) Risk categories should be established based on the antibody and the XM results obtained. (b) DSA detected by CDC and a positive XM should be avoided due to their strong association with antibody-mediated rejection and graft loss. (c) A renal transplantation can be performed in the absence of a prospective XM if single-antigen bead screening for antibodies to all class I and II HLA loci is negative. This decision, however, needs to be taken in agreement with local clinical programs and the relevant regulatory bodies. (d) The presence of DSA HLA antibodies should be avoided in heart and lung transplantation and considered a risk factor for liver, intestinal, and islet cell transplantation. Posttransplantation Group: (a) High-risk patients (i.e., desensitized or DSA positive/XM negative) should be monitored by measurement of DSA and protocol biopsies in the first 3 months after transplantation. (b) Intermediate-risk patients (history of DSA but currently negative) should be monitored for DSA within the first month. If DSA is present, a biopsy should be performed. (c) Low-risk patients (nonsensitized first transplantation) should be screened for DSA at least once 3 to 12 months after transplantation. If DSA is detected, a biopsy should be performed. In all three categories, the recommendations for subsequent treatment are based on the biopsy results.

CONCLUSIONS

A comprehensive list of recommendations is provided covering the technical and pretransplantation and posttransplantation monitoring of HLA antibodies in solid organ transplantation. The recommendations are intended to provide state-of-the-art guidance in the use and clinical application of recently developed methods for HLA antibody detection when used in conjunction with traditional methods.

Renal graft survival is not influenced by a positive flow B-cell crossmatch

INTRODUCTION

The influence of a positive B-cell crossmatch on graft outcome in renal transplantation is controversial.

METHODS

We analyzed graft survival using Kaplan-Meier estimates for recipients of deceased donor kidneys who were either regraft transplant patients (n = 198) from 1990 to August 20, 2004, or primary transplant patients (n = 361) from December 15, 2000 to August 8, 2004, each of whom had a flow T- and B-cell IgG crossmatch performed before transplantation. The flow B-cell crossmatch (FBXM) was not used to decide whether or not to transplant. Graft survival was analyzed by whether the patient's FBXM was positive or negative. We also evaluated creatinine levels and graft survival of 131 transplant patients (June 1, 2004 to July 1, 2005) by their FBXM result and by their HLA class II flow-defined IgG PRA.

RESULTS

One- and three-yr graft survival for the primary transplant patient group with a positive FBXM (98% and 84%) was not significantly different from the group with a negative FBXM (96% and 93%) (log-rank = 0.9). Similarly, graft survival at one, five, and 10 yr for the regraft transplant group whose FBXM was positive (91%, 76%, and 61%) was not significantly different from the group whose FBXM was negative (91%, 79%, and 77%) (log-rank = 0.4). Creatinine levels in the group of patients whose FBXM was positive (1.4 +/- 0.4 mg/dL; n = 76) were not significantly different from the group with a negative FBXM (1.4 +/- 0.4 mg/dL; n = 42). Even in the presence of class II PRA, a positive FBXM did not impact a patient's creatinine levels or graft outcome.

CONCLUSION

Neither short nor long-term graft survival of deceased donor kidneys is influenced by a positive flow B-cell IgG crossmatch, even when caused by HLA class II antibody.