ABO-incompatible kidney transplantation enabled by non-antigen-specific immunoadsorption

Effect of ABO Mismatch and Red Blood Cell Alloimmunization on the Outcome of Hematopoietic Cell Transplantation for Sickle Cell Disease

Hematopoietic stem cell transplantation (HCT) remains the sole well-established curative option for patients with sickle cell disease (SCD). Nonmyeloablative conditioning has been used to improve outcomes and reduce toxicities in adult SCD patients. However, recipient-donor ABO incompatibility and alloimmunization may be significant impediments to successful outcomes of HSCT in SCD patients owing to risks of hemolysis, delayed engraftment, poor graft function, and graft failure (GF). Here we report our experience with allogeneic HCT for SCD and the effects of RBC group mismatch and alloimmunization on the outcome of transplant recipients. We conducted a retrospective analysis of all SCD patients age >14 years who underwent HCT between January 2015 and February 2022 at our center. All patients received i.v. alemtuzumab (1 mg/kg divided over 5 days on days -7 to -3) and 300 cGy total body irradiation on day -2 or -1 for conditioning. Pretransplantation preparation consisted of hydroxyurea at the maximum tolerated dose for 2 to 3 months and 1 session of exchange transfusion. Peripherally mobilized CD34 stem cells targeting 10 × 106 /kg of recipient weight were used. For graft-versus-host disease prophylaxis, sirolimus was started on day -1 and continued for 1 year with tapering if lymphoid chimerism was >50%. For patients with major ABO incompatibility, we administered 2 doses of rituximab (375 mg/m2) and 3 sessions of plasmapheresis before starting the conditioning regimen, targeting an isohemagglutinin titer <1/32. The primary objective was to determine the impact of RBC group mismatch and alloimmunization on the outcomes of the HCT recipients. The secondary objective was to assess the impact of GF on overall survival (OS). Logistic regression was done to evaluate predictors for GF. The Kaplan-Meier method was used for survival analysis. A total of 194 patients were included, with a median age of 26 years. Their median baseline hemoglobin and hemoglobin S values were 93 g/L and 71.3%, respectively. Indications for HCT included recurrent vaso-occlusive crisis in 52.5% of the patients, central nervous system events in 19.6%, and acute chest syndrome in 17%. After a median follow-up of 28.8 months (range, 5 to 83 months), 16 patients (8%) experienced GF (3 with primary GF and 13 with secondary GF). On univariate analysis, ABO minor incompatibility and RBC alloantibodies against donor non-ABO antigens were predictive of GF. On multivariate analysis, RBC alloantibodies against donor non-ABO antigens (odds ratio, 8.29; 95% confidence interval, 2.01 to 34.05; P = .0033) was the sole factor predictive of GF. None of the 16 patients with major ABO incompatibility developed GF. The 2-year OS for all patients was 95%. The 2-year OS was 98% in patients without GF, compared to 74% in patients with GF (P < .0001). In our SCD patients who underwent HSCT, the presence of RBC alloantibodies against donor non-ABO antigens was an independent risk factor for GF. Patients with GF had inferior survival, and strategies for decreasing the risk of GF are needed.

Non-antigen-specific Immunoadsorption Is a Risk Factor for Severe Postoperative Infections in ABO-Incompatible Kidney Transplant Recipients

ABO-incompatible (ABOi) living kidney transplantation (KTx) is an established procedure to address the demand for kidney transplants with outcomes comparable to ABO-compatible KTx. Desensitization involves the use of immunoadsorption (IA) to eliminate preformed antibodies against the allograft. This monocentric retrospective study compares single-use antigen-selective Glycosorb® ABO columns to reusable non-antigen-specific Immunosorba® immunoglobulin adsorption columns regarding postoperative infectious complications and outcome. It includes all 138 ABOi KTx performed at Freiburg Transplant Center from 2004-2020. We compare 81 patients desensitized using antigen-specific columns (sIA) to 57 patients who received IA using non-antigen-specific columns (nsIA). We describe distribution of infections, mortality and allograft survival in both groups and use Cox proportional hazards regression to test for the association of IA type with severe infections. Desensitization with nsIA tripled the risk of severe postoperative infections (adjusted HR 3.08, 95% CI: 1.3-8.1) compared to sIA. nsIA was associated with significantly more recurring (21.4% vs. 6.2%) and severe infections (28.6% vs. 8.6%), mostly in the form of urosepsis. A significantly higher proportion of patients with sIA suffered from allograft rejection (29.6% vs. 14.0%). However, allograft survival was comparable. nsIA is associated with a two-fold risk of developing a severe postoperative infection after ABOi KTx.

Intravenous immunoglobulin in kidney transplantation: Mechanisms of action, clinical applications, adverse effects, and hyperimmune globulin

Intravenous immunoglobulin (IVIG) has been developed for over 40 years. The mechanisms of action of IVIG are complex and diverse, and there may be multiple mechanisms that combine to influence it. IVIG has been used in kidney transplantation for desensitization, treatment of antibody-mediated rejection, and ABO-incompatible transplantation. and treatment or prevention of some infectious diseases. Hyperimmune globulins such as cytomegalovirus hyperimmune globulin (CMV-IG) and hepatitis B hyperimmune globulin (HBIG) have also been used to protect against cytomegalovirus and hepatitis B virus, respectively. However, IVIG is also associated with some rare but serious adverse effects and some application risks, and clinicians need to weigh the pros and cons and develop individualized treatment programs to benefit more patients. This review will provide an overview of the multiple mechanisms of action, clinical applications, adverse effects, and prophylactic measures of IVIG, and hyperimmune globulin will also be introduced in it.

Immunoadsorption and plasmapheresis at the ICU - A description of the frequencies and indications in a single center experience and a case report

Immunologically mediated diseases can lead to severe courses that have to be treated in an intensive care unit. The use of extracorporeal organ support systems (ventilation, ECMO) is common. A therapeutic principle for these diseases is the removal of disease-causing antibodies. This can be done nonspecifically by plasmapheresis or specifically by immune adsorption. While most intensive care units have the facilities for plasmapheresis (membrane plasma filtration), immunoadsorption is much less common. Over a period of 10 years, the numbers of immunoadsorption and plasmapheresis treatments performed in a single center intensive care unit are shown according to their indication (IA: 18 Pts, 58 treatments. PA: 54 Pts, 148 treatments). A case study of a patient with granulomatosis with polyangiitis shows the successful treatment with immunoadsorption. The advantages of immunoadsorption in patients with complex coagulation disorders and a critical clinical picture in terms of SIRS and ARDS are shown.

Recommendations for living donor kidney transplantation

This Guide for Living Donor Kidney Transplantation (LDKT) has been prepared with the sponsorship of the Spanish Society of Nephrology (SEN), the Spanish Transplant Society (SET), and the Spanish National Transplant Organization (ONT). It updates evidence to offer the best chronic renal failure treatment when a potential living donor is available. The core aim of this Guide is to supply clinicians who evaluate living donors and transplant recipients with the best decision-making tools, to optimise their outcomes. Moreover, the role of living donors in the current KT context should recover the level of importance it had until recently. To this end the new forms of incompatible HLA and/or ABO donation, as well as the paired donation which is possible in several hospitals with experience in LDKT, offer additional ways to treat renal patients with an incompatible donor. Good results in terms of patient and graft survival have expanded the range of circumstances under which living renal donors are accepted. Older donors are now accepted, as are others with factors that affect the decision, such as a borderline clinical history or alterations, which when evaluated may lead to an additional number of transplantations. This Guide does not forget that LDKT may lead to risk for the donor. Pre-donation evaluation has to centre on the problems which may arise over the short or long-term, and these have to be described to the potential donor so that they are able take them into account. Experience over recent years has led to progress in risk analysis, to protect donors' health. This aspect always has to be taken into account by LDKT programmes when evaluating potential donors. Finally, this Guide has been designed to aid decision-making, with recommendations and suggestions when uncertainties arise in pre-donation studies. Its overarching aim is to ensure that informed consent is based on high quality studies and information supplied to donors and recipients, offering the strongest possible guarantees.

Use of immunoadsorption columns in ABO-incompatible renal transplantation: A prospective study at a tertiary care center in India

BACKGROUND

We present our experience of ABO-incompatible renal transplant using immunoadsorption (IA) columns. We have compared efficacy of two commercially available columns.

METHODS

This single-center prospective study was conducted at Army Hospital Research and Referral, Delhi. All consecutive ABO-incompatible renal transplants from January 2014 to February 2018 were analyzed. Of 30 patients who underwent transplantations, 28 underwent antibody depletion with immunoadsorption columns. Of them, 14 cases were in the "Glycosorb group," while 14 in the "Adsopak group."

RESULTS

The donors in the Adsopak group were older than those in the Glycosorb group (p < 0.05). Both groups had spousal donors in majority. The cutoff for the antibody titer was 1:8. The median titer in the Adsopak group was 128 (range, 1:4 to 1:2048), while that in the Glycosorb group was 24 (range, 1:8 to 1:128). All patients in the Glycosorb group had baseline titers ≤1:128, while 13 patients in the Adsopak group had baseline titers ≤1:512. Nil titer was achievable with Glycosorb® (50%,7/14) but not with Adsopak® (P < 0.01). Around 4 sessions were required for the Glycosorb group, while around 8 sessions were required for the Adsopak group before transplantation (p < 0.001). The Glycosorb group was advantageous in terms of graft failure because no rejection was noticed in these patients in their follow-up period. Three patients in the Adsopak group developed rejection (two had mixed rejection, and one had antibody-mediated rejection). Four patients died of sepsis (three in the Glycosorb and one in the Adsopak group). Lower baseline serum creatinine level was achieved in the Glycosorb group.

CONCLUSIONS

Results of ABO-incompatible renal transplantation were satisfactory, and the use of immunoadsorption columns could effectively deplete antibody titers. Glycosorb columns were more efficient than Adsopak columns. Graft survival was better with Glycosorb. Posttransplant infections were a major cause of mortality.

Immunoadsorption Column Reuse

Introduction:

Selective immunoadsorption (IA) is a technique to remove preformed Anti-ABO antibodies in ABO-incompatible renal transplants (ABOiRT). Since the cost of a single IA column is high and single use rarely achieves the target anti-ABO titers, its use is not widely spread. We studied the safety and efficacy of the reuse of IA columns in ABOiRT.

Methods:

Single-center, retrospective analysis of all patients who underwent ABOiRT with IA column reuse from January 2016 to July 2018. The column was reused after sterilization with ethylene oxide and flushed with normal saline before use. Target titers (IgG) were 1:4 preoperatively. Baseline IgG titers, plasma volume processed in each session, postoperative titer rebound were recorded. The primary outcome was IgG titer reduction after each use and adverse reaction during the IA column reuse. Patients were followed up until 1 year.

Results:

16 patients underwent ABOiRT using IA columns. Baseline IgG titer ranged from 1:32 to 1:512. Reuse of IA column was done 23 times and underwent 2^nd reuse for 9 times. The average plasma volume treated was 22 L. Efficacy of the IA column in log titer reduction of anti-ABO titer was 4 logs after the first use, 3 logs after 1^st reuse, and 1.5 logs after 2^nd reuse. 12 (75%) patients successfully reached the target IgG titer of ≤1:4 solely with column reuse. One patient received a single session of plasma exchange before transplantation. Postoperatively, one patient received one session of plasma exchange due to a rebound in anti-ABO antibodies. No serious side effects were noted during the reuse.

Conclusion:

IA column reuse up to two times showed efficacy in the successful reduction of antibody titers. Column reuse was not associated with any significant side effects.

The First North American Experience Using Glycosorb Immunoadsorption Columns for Blood Group-Incompatible Kidney Transplantation

Background:

Blood group incompatibility (ABOi) is the most common barrier to living donor kidney transplantation. Options for such recipients include kidney paired donation (KPD) or desensitization methodology to reduce blood antibody response.

Objective:

The objective of this study is to report on the first North America experience in ABOi living donor kidney transplantation using Glycosorb ABO immunoadsorption columns.

Design:

Retrospective observational cohort study.

Setting:

Renal transplant program at St. Michael’s Hospital, Unity Health Toronto, University of Toronto.

Patients:

Twenty-six ABOi living donor transplants from August 2011 through February 2020 were undertaken at our center.

Measurements:

Renal allograft and patient survival postdesensitization for ABOi living donor transplants and isohemagglutinin titer reduction.

Methods:

Preoperative immunosuppressive regimen consisted of a single dose of Rituximab 375 mg/m² IV on day −28; tacrolimus, mycophenolic acid, and prednisone to start on day −7. Immunoadsorption treatments with Glycosorb A or B columns were performed on day −7 through day −1 based on anti-A or anti-B titers on Spectra Optia Apheresis System. Immunosuppression included basiliximab, solumedrol followed by oral prednisone, once-daily tacrolimus, and mycophenolic acid. The mean follow-up was 53 months (3-96 months).

Results:

A total of 26 individuals underwent an attempt at desensitization of whom 24 patients underwent immediate transplant. One patient had a rebound in titers and subsequently was transplanted from a blood group compatible living donor. A second patient had an unrelated medical issue and desensitization was discontinued. Five-year patient survival was 96% and death censored allograft survival was 92%. Posttransplant anti-A or anti-B titers were monitored daily for the first 7 days posttransplant and every 2 days from days 7 to 14. There were no acute rejections seen in this cohort of transplant recipients.

Limitations:

As our protocol was first initiated as proof of concept, a few recipients had low initial isohemagglutinin titers. This may have contributed to improved clinical outcomes.

Conclusions:

ABO column immunoadsorption with specific columns is a safe and effective method for ABOi living donor kidney transplantation, and an option when KPD is less than ideal.

Trial not registered as this was a retrospective cohort review.

ABO-incompatible living kidney transplantation

ABO-incompatible living kidney transplantation is nowadays a routine procedure to expand living donor pool. The past decades have seen the evolution of desensitization protocol and immunosuppression regimen. Despite increased bleeding events, infectious complications, and rejection episodes reported in some studies, favorable graft and patient survival rate are now achieved, regardless of various protocols among transplant centers. Several issues such as the usage of rituximab and standardization of blood group antibody titration remain to be settled. The deposition of C4d is no longer the histopathologic hallmark of antibody-mediated rejection, which have inspired innovative strategies of peripheral molecular screening and the improvement of histological diagnosis of AMR (antibody-mediated rejection). The better understanding of the underlying mechanism might facilitate the distinction and therapeutic schemes of AMR.

Current protocols and outcomes of ABO-incompatible kidney transplantation

One of the principal obstacles in transplantation from living donors is that approximately 30% are immunologically incompatible because of the presence in the recipient of antibodies directed against the human leukocyte antigen system of the donor or because of the incompatibility of the ABO system. The aim of this review is to describe the more recent data from the literature on the different protocols used and the clinical outcomes of ABO-incompatible kidney transplantation. Two different strategies are used to overcome these barriers: desensitization of the recipient to remove the antibodies and to prevent their rebound after transplantation and the exchange of organs between two or more pairs. The largest part of this review is dedicated to describing the techniques of desensitization. Even if the first reports of successful renal transplantation between ABO-incompatible pairs have been published by 1980, the number of ABO-incompatible transplants increased substantially in this century because of our improved knowledge of the immune system and the availability of new drugs. Rituximab has substantially replaced splenectomy. The technique of apheresis has improved and more recently a tailored desensitization proved to be the more efficient strategy avoiding an excess of immunosuppression with the related side effects. Recent reports document outcomes for such transplantation similar to the outcomes of standard transplantation.

Successful use of nonantigen-specific immunoadsorption with antihuman Ig-columns in kidney graft antibody-mediated rejection

INTRODUCTION

Nonantigen-specific immunoadsorption (IA) has proven to be effective in acute antibody-mediated rejection (aAMR). However, there is a lack of solid studies evaluating the safety and efficacy of IA with antihuman Ig-columns in aAMR. For chronic-active AMR (cAMR), no studies have evaluated the efficacy of nonantingen-specific IA with antihuman Ig-columns. The purpose of this study was to evaluate the role of nonantigen-specific IA with antihuman Ig-columns in the treatment of both aAMR and cAMR in kidney transplantation.

MATERIAL AND METHODS

In retrospective and observational study, kidney graft and recipient survival rates were assessed after treatment of aAMR and cAMR with nonantigen-specific IA with Ig-Flex columns (Therasorb) between January 2012 and May 2018. Protocols included nonantigen-specific IA, rituximab, intravenous immunoglobulin, and rescue plasma exchange, if necessary.

RESULTS

The study included 14 patients with AMR (acute in 9, chronic active in 5). For aAMR, mean follow-up was 13 ± 6 months, and patient and graft survival were, respectively, of 100% and 83%, with a mean increase in estimated glomerular filtration rate (eGFR) of 7.98 ± 12.96, 10.18 ± 16.71, and 11.43 ± 13.85 mL/min/1.72 m² (P > .05) at 3, 12 months after treatment, and at the end of follow-up, respectively. For cAMR, mean follow-up was 14 ± 8 months, and patient and graft survival were, respectively, of 100% and 60%, with an average increase in eGFR of 4.30 ± 7.86, 5.64 ± 10.47, and 14.5 ± 7.86 mL/min/m² (P > .05) at 3, 12 months after IA treatment, and at the end of the follow-up, respectively, although 40% did not respond and required chronic hemodialysis.

CONCLUSION

Nonantigen-specific IA with Ig-Flex columns was safe and effective for aAMR treatment in kidney transplantation. In cAMR, IA with Ig-Flex columns was associated with a satisfactory kidney graft survival, suggesting that IA could potentially offer some benefits supporting its indication in cAMR.

Selective plasma exchange in ABO-incompatible kidney transplantation: comparison of substitution with albumin and partial substitution with fresh frozen plasma

We have performed selective plasma exchange (SePE) as apheresis before ABO-incompatible kidney transplantation since 2015. In this study, we divided the SePE sessions into two groups, those using albumin alone (Group A) and those partially using fresh frozen plasma (FFP) (Group F), and compared their clinical efficacies. A total of 58 sessions of SePE (Group A: n = 41, Group F: n = 17) were performed in 30 recipients of ABOi kidney transplantation during the study period and the decrease in isoagglutinin titers, changes in the levels of serum IgG and IgM as well as coagulation factors (fibrinogen, factor XIII), and incidence of side effects were retrospectively compared. There was a more significant decrease of isoagglutinin titers in Group F compared to Group A. Immunoglobulins and coagulants were replenished in Group F. Meanwhile, the incidence of side effects was significantly higher in Group F. SePE using FFP, which can effectively decrease isoagglutinins titers and replenish immunoglobulin and coagulation factors, may be a beneficial treatment modality as apheresis before ABO-incompatible kidney transplantation, in spite of a disadvantage that there are many side effects.

Therapeutic apheresis in kidney transplantation: An updated review

Therapeutic apheresis is a cornerstone of therapy for several conditions in transplantation medicine and is available in different technical variants. In the setting of kidney transplantation, immunological barriers such as ABO blood group incompatibility and preformed donor-specific antibodies can complicate the outcome of deceased- or living- donor transplantation. Postoperatively, additional problems such as antibody-mediated rejection and a recurrence of primary focal segmental glomerulosclerosis can limit therapeutic success and decrease graft survival. Therapeutic apheresis techniques find application in these issues by separating and selectively removing exchanging or modifying pathogenic material from the patient by an extracorporeal aphaeresis system. The purpose of this review is to describe the available techniques of therapeutic aphaeresis with their specific advantages and disadvantages and examine the evidence supporting the application of therapeutic aphaeresis as an adjunctive therapeutic option to immunosuppressive agents in protocols before and after kidney transplantation.

The degree of major histocompatibility complex matching between purebred Maltese and mongrel dogs using microsatellite markers

Long-term maintenance of transplanted organs is one of the major factors that increases survival time of recipients. Although obtaining a major histocompatibility complex (MHC)-matched donor with the recipient is essential for successful organ transplantation, there have been limited reports on MHC matching between dogs. In this study, we analyzed the canine MHC matching rates using Maltese, one of the most popular purebred dogs, and mongrel dogs in Korea. Genomic DNA was extracted from blood leukocytes and DNA was amplified by polymerase chain reaction with primers specific to MHC microsatellite markers. The MHC matching degree was confirmed by the microsatellite markers using polyacrylamide gel electrophoresis. The MHC matching rates of each donor-recipient groups including Maltese-Maltese, mongrel-mongrel and Maltese-mongrel were 4.76%, 5.13% and 6.67%, respectively. There were no significant differences in the MHC matching degree between each group. These results demonstrate that MHC-matched donors could be selected from other breeds as much as from the same breed for transplantation. Knowledge of the MHC matching degree of purebred and mongrel dogs would offer valuable information not only for improving the success rate of organ transplantation surgery in canine patients but also for transplantation research using experimental canine models.

Dual targeting: Combining costimulation blockade and bortezomib to permit kidney transplantation in sensitized recipients

Previous evidence suggests that a homeostatic germinal center (GC) response may limit bortezomib desensitization therapy. We evaluated the combination of costimulation blockade with bortezomib in a sensitized non-human primate kidney transplant model. Sensitized animals were treated with bortezomib, belatacept, and anti-CD40 mAb twice weekly for a month (n = 6) and compared to control animals (n = 7). Desensitization therapy-mediated DSA reductions approached statistical significance (P = .07) and significantly diminished bone marrow PCs, lymph node follicular helper T cells, and memory B cell proliferation. Graft survival was prolonged in the desensitization group (P = .073). All control animals (n = 6) experienced graft loss due to antibody-mediated rejection (AMR) after kidney transplantation, compared to one desensitized animal (1/5). Overall, histological AMR scores were significantly lower in the treatment group (n = 5) compared to control (P = .020). However, CMV disease was common in the desensitized group (3/5). Desensitized animals were sacrificed after long-term follow-up with functioning grafts. Dual targeting of both plasma cells and upstream GC responses successfully prolongs graft survival in a sensitized NHP model despite significant infectious complications and drug toxicity. Further work is planned to dissect underlying mechanisms, and explore safety concerns.

Resultados de la inmnuadsorción en el trasplante ABOi y el rechazo humoral en una unidad de hemodiáilsis hospitalaria

INTRODUCCIÓN El tratamiento con inmunoadsorción no selectiva fue introducido en nuestra unidad de hemodiálisis hospitalaria con el objetivo de permitir la desensibilización previa a un trasplante renal con incompatibilidad de grupo sanguíneo y el tratamiento del rechazo mediado por anticuerpos. OBJETIVO Analizar los resultados de la técnica de inmunoadsorción no selectiva, en una unidad de hemodiálisis hospitalaria. MATERIAL Y MÉTODOS Estudio retrospectivo, descriptivo, de los primeros 18 pacientes tratados en nuestro centro con inmunoadsorción no selectiva (años 2012-2017) en las indicaciones de acondicionamiento del trasplante ABOi y tratamiento del rechazo humoral. RESULTADOS Durante un periodo de 5 años se analizaron un total de 128 sesiones de inmunoadsorción no selectiva. El 38,9% (n=7) de los casos para desensibilización previa al trasplante renal con incompatibilidad de grupo sanguíneo y el 61,1% (n=11) restante para el tratamiento del rechazo mediado por anticuerpos. En el primer caso, realizaron una media de 8±0,6 sesiones de inmunoadsorción previas al trasplante renal y el 57,1% se complementaron 2 sesiones posteriores. El tratamiento concomitante fue el protocolizado con Rituximab e inmunoglobulinas, requiriendo el 57,1% la realización de recambios plasmáticos. En el segundo caso, realizaron una media de 5,9±2 sesiones de inmunoadsorción. El tratamiento concomitante fue el mismo y el 27,3% realizaron recambios plasmáticos. CONCLUSIONES El trasplante renal de donante vivo ABOi tras la desensibilización fue posible en el 100% de los pacientes. El 72,7% de los pacientes tratados para el rechazo mediado por anticuerpos mantienen actualmente la funcionalidad del injerto.

Pediatric ABO-incompatible kidney transplantation: Evolving with the advancing apheresis technology: A single-center experience

Recent literature has endorsed favorable outcomes following ABOi kidney transplantation in pediatric population. Nevertheless, reluctance to pursue an ABOi still remains pervasive. This could be ascribed to various legitimate reasons, namely less extensive pediatric ABOi data, technical difficulties encountered during PP, cost restraints, and concerns regarding higher rates of antibody-mediated rejection, infectious complications, and post-transplant lymphoproliferative disorder as compared to adults. However, given the similar excellent outcomes of both ABOi and ABOc kidney transplantation, clinicians should consider this option sooner if a compatible donor or swap is not available. Here, we describe the outcomes of three pediatric ABOi performed at our institute in India (from 2014 till now), wherein distinct apheresis modalities had been employed in each desensitization protocol, and our techniques evolved with advancing science in apheresis. This case series includes India's first published pediatric ABO-incompatible transplant (Case 2) and the youngest child to undergo ABO-incompatible renal transplant in SAARC nations (Case 3).

ABO-Incompatible Kidney Transplantation

ABO-incompatible (ABOi) kidney transplantation has long been considered a contraindication to successful kidney transplantation. During the last 25 years, increasing organ shortage enforced the development of strategies to overcome the ABO antibody barrier. In the meantime, ABOi kidney transplantation has become a routine procedure with death-censored graft survival rates comparable to the rates in compatible transplantations. Desensitization is usually achieved by apheresis and B cell-depleting therapies that are accompanied by powerful immunosuppression. Anti-A/B antibodies are aimed to be below a certain threshold at the time of ABOi kidney transplantation and during the first 2 weeks after surgery. Thereafter, even a rebound of anti-A/B antibodies does not appear to harm the kidney transplant, a phenomenon that is called accommodation, but is poorly understood. There is still concern, however, that infectious complications such as viral disease, Pneumocystis jirovecii pneumonia, and severe urinary tract infections are increased after ABOi transplantations. Recent data from the Collaborative Transplant Study show that during the first year after kidney transplantation, one additional patient death from an infectious complication occurs in 100 ABOi kidney transplant recipients. Herein, we review the recent evidence on ABOi kidney transplantation with a focus on desensitization strategies and respective outcomes.

Clinical outcomes with ABO antibody titer variability in a multicenter study of ABO-incompatible kidney transplantation in the United Kingdom

BACKGROUND

ABO blood group-incompatible kidney transplantation (ABOiKTx) outcomes are good, but complications are more common than in conventional transplantation. Regimens that use extracorporeal antibody removal therapy (EART) and enhanced immunosuppression are guided by titration of ABO blood group antibodies (using hemagglutination [HA] dilution assays), and these assays vary significantly in performance between centers. This study aims to describe the differences in titer measurement and the effect on clinical practice and outcomes.

STUDY DESIGN AND METHODS

This multicentre, prospective cohort study of 100 ABOiKTx recipients assessed treatment and outcome data, including HA assay results measured retrospectively in a single central laboratory.

RESULTS

Patient and allograft survival at 1 year was 99% and 94%, respectively. There were significant differences in the number of pretransplantation EART sessions in centers undertaking plasma exchange (PEx), compared with immunoadsorption (IA) (median, 6 vs. 4 sessions; p = 0.007). The pre-EART HA titer in both groups was the same when centrally assayed. The local HA assay used to guide treatment yielded significantly higher titers in centers undertaking PEx compared with IA (median, 128 vs. 32; p < 0.005). Patients undergoing PEx rather than IA were significantly more likely to suffer postoperative hematoma (12.9% vs. 1.8%; p = 0.05) or any perioperative collection requiring drainage (19.4% vs. 3.6%; p = 0.02).

CONCLUSION

The colinearity of HA assay sensitivity with the receipt of PEx and EART limits some conclusions regarding the likely direction of causation. However, the association of differences in clinical practice with recognized perioperative complications of ABOiKTx identifies targets for further investigation and quality improvement.

Economic Impacts of ABO-Incompatible Live Donor Kidney Transplantation: A National Study of Medicare-Insured Recipients

The infrequent use of ABO-incompatible (ABOi) kidney transplantation in the United States may reflect concern about the costs of necessary preconditioning and posttransplant care. Medicare data for 26 500 live donor kidney transplant recipients (2000 to March 2011), including 271 ABOi and 62 A2-incompatible (A2i) recipients, were analyzed to assess the impact of pretransplant, transplant episode and 3-year posttransplant costs. The marginal costs of ABOi and A2i versus ABO-compatible (ABOc) transplants were quantified by multivariate linear regression including adjustment for recipient, donor and transplant factors. Compared with ABOc transplantation, patient survival (93.2% vs. 88.15%, p = 0.0009) and death-censored graft survival (85.4% vs. 76.1%, p < 0.05) at 3 years were lower after ABOi transplant. The average overall cost of the transplant episode was significantly higher for ABOi ($65 080) compared with A2i ($36 752) and ABOc ($32 039) transplantation (p < 0.001), excluding organ acquisition. ABOi transplant was associated with high adjusted posttransplant spending (marginal costs compared to ABOc - year 1: $25 044; year 2: $10 496; year 3: $7307; p < 0.01). ABOi transplantation provides a clinically effective method to expand access to transplantation. Although more expensive, the modest increases in total spending are easily justified by avoiding long-term dialysis and its associated morbidity and cost.

Discontinuation of steroids in ABO-incompatible renal transplantation

A steroid-free protocol for ABO-compatible renal transplantation has been used at our center since 1983. To minimize the adverse effects of steroids, we also developed a steroid sparing protocol for ABO-incompatible renal transplantation in 2008. The present study is a report of our results. A retrospective review of the first 50 ABO-incompatible renal transplantations performed at a single university center. If no immunological events occurred in the post-transplant period, prednisolone tapering was initiated approximately 3 months after transplantation. Forty-three patients completed prednisolone tapering after 289 ± 58 days. Three patients died during follow-up, and four patients lost graft function. None of these adverse events were rejection related. Eleven patients experienced rejections; seven were on prednisolone and four were after weaning from prednisolone. All patients responded well to antirejection treatment. Overall, 1-year rejection rate was 19%. One- and 3-year graft survival was 94% and 91%, respectively. One-year post-transplant median serum creatinine was 123 μmol/L. We found acceptable rejection rates, graft survival, and creatinine levels in patients undergoing ABO-incompatible renal transplantations with a steroid sparing protocol. However, a longer follow-up of a lager cohort is needed before firm conclusions can be made.

Outcomes Following ABO-Incompatible Kidney Transplantation Performed After Desensitization by Nonantigen-Specific Immunoadsorption

BACKGROUND

For desensitization of ABO-incompatible kidney transplant recipients we recently proposed nonantigen-specific immunoadsorption (IA) and rituximab.

METHODS

We now compared clinical outcomes of 34 ABO-incompatible living-donor kidney recipients who were transplanted using this protocol with that of 68 matched ABO-compatible patients. In addition, we analyzed efficacy and cost of nonantigen-specific as compared to blood group antigen-specific IA.

RESULTS

Before desensitization, the median isoagglutinin titer of 34 ABO-incompatible patients was 1:64 (Coombs technique). Patients received a median of 7 preoperative IA treatments. Twenty-four patients had a median of 2 additional plasmapheresis treatments to reach the preoperative target isoagglutinin titer of 1:8 or less. After a median postoperative follow-up of 22 months, overall graft survival in the ABO-incompatible group was not significantly different from that in ABO-compatible patients (log-rank P = 0.20), whereas patient survival tended to be lower (log-rank P = 0.05). The incidence of rejection episodes was 15% in both groups. The ABO-incompatible kidney recipients had a higher incidence of BK virus replication (P = 0.04) and nephropathy (P = 0.01) and showed more often colonization with multidrug resistant bacteria (P = 0.02). In comparison to blood group antigen-specific IA, nonantigen-specific IA showed equal efficacy but was associated with reduction in cost.

CONCLUSIONS

Clinical outcomes of ABO-incompatible patients desensitized with a nonantigen-specific IA device and rituximab do not differ from that of matched ABO-compatible patients although a trend toward reduced patient survival was noted. Special attention must be paid to the higher incidence of BK virus infection in recipients of ABO-incompatible grafts.

Strategies to overcome the ABO barrier in kidney transplantation

Kidney transplantation across the ABO blood group barrier was long considered a contraindication for transplantation, but in an effort to increase donor pools, specific regimens for ABO-incompatible (ABOi) transplantation have been developed. These regimens are now widely used as an integral part of the available treatment options. Various desensitization protocols, commonly based on transient depletion of preformed anti-A and/or anti-B antibodies and modulation of B-cell immunity, enable excellent transplant outcomes, even in the long-term. Nevertheless, the molecular mechanisms behind transplant acceptance facilitated by a short course of anti-humoral treatment are still incompletely understood. With the evolution of efficient clinical programmes, tailoring of recipient preconditioning based on individual donor-recipient blood type combinations and the levels of pretransplant anti-A/B antibodies has become possible. In the context of low antibody titres and/or donor A2 phenotype, immunomodulation and/or apheresis might be dispensable. A concern still exists, however, that ABOi kidney transplantation is associated with an increased risk of surgical and infectious complications, partly owing to the effects of extracorporeal treatment and intensified immunosuppression. Nevertheless, a continuous improvement in desensitization strategies, with the aim of minimizing the immunosuppressive burden, might pave the way to clinical outcomes that are comparable to those achieved in ABO-compatible transplantation.

Current progress in ABO-incompatible kidney transplantation

ABO-incompatible kidney transplantation (ABOi KT) was introduced to expand the donor pool and minimize shortage of kidneys for transplantation. Because improved outcomes of ABOi KT were reported in Japan in the early 2000s, the number of ABOi KTs has been increasing worldwide. In addition, a better understanding of immune pathogenesis and subsequent aggressive immunosuppression has helped to make effective desensitization protocols. Current strategies of ABOi KT consist of pretransplant antibody removal using plasmapheresis or immunoadsorption to prevent hyperacute rejection and potent maintenance immunosuppression, such as tacrolimus and mycophenolate mofetil, to inhibit antibody-mediated rejection. Recent outcomes of ABOi KT are comparable with ABO-compatible KT. However, there are still many problems to be resolved. Very high anti-ABO antibody producers are difficult to desensitize. In addition, ABOi KT is associated with an increased risk of infection and possibly malignancy due to aggressive immunosuppression. Optimization of desensitization and patient-tailored immunosuppression protocols are needed to achieve better outcomes of ABOi KT. This review provides an overview of the history, immune mechanism, immunosuppressive protocol, outcomes, current obstacles, and future perspectives in ABOi KT.

Antigen-Specific versus Non-Antigen-Specific Immunoadsorption in ABO-Incompatible Renal Transplantation

Introduction

ABO-incompatible (ABOi) renal transplantation (RTx) from living donors is an established procedure to expand the donor pool for patients with end stage renal disease. Immunoadsorption (IA) is a standard procedure for the removal of preformed antibodies against the allograft. In this study, antigen-specific and non-antigen-specific IA in ABOi RTx were compared.

Patients and Methods

10 patients underwent antigen-specific IA (Glycosorb group) and 13 patients non-antigen-specific IA (Immunosorba group). The effects of both procedures regarding antibody reduction, number of treatments, complications, costs, as well as the allograft function and patient survival were compared between both groups.

Results

Although the IgG levels were reduced equally by both procedures (p=0.82), the reduction of the IgM level was more effective in the Glycosorb group (p=0.0172). Patients in both groups required a median number of 6 IA before ABOi RTx. Allograft function at one year after AB0i RTx was similar in both groups (estimated glomerular filtration rate: 66 vs. 64 ml/min/1.73m² respectively), with a death-censored graft survival of 90.0% and 92.3% respectively. Complication rates did not differ between procedures. Due to the reuse of non-antigen-specific Immunosorba columns, costs were considerably lower in this group; however, the use of the Immunosorba-based IA was less time-efficient.

Conclusion

Considering upcoming alternatives as simultaneous performance of dialysis and IA or a possible reuse of Glycosorb columns, this might become less relevant in the future.

Three-year outcomes following 1420 ABO-incompatible living-donor kidney transplants performed after ABO antibody reduction: results from 101 centers

BACKGROUND

Reports from experienced centers suggest that recipients of an ABO-incompatible living-donor kidney transplant after reduction of ABO antibodies experience no penalty in graft and patient survival versus ABO-compatible transplants, but confirmation that these results can be widely replicated is lacking.

METHODS

Living-donor kidney transplants from ABO-incompatible donors after ABO antibody reduction registered with the Collaborative Transplant Study during 2005 to 2012 were analyzed and compared with (i) a matched group of ABO-compatible transplant recipients and (ii) all ABO-compatible transplants from centers that performed at least five ABO-incompatible grafts during the study period.

RESULTS

One thousand four hundred twenty living-donor ABO-incompatible kidney transplants were analyzed. Three-year death-censored graft survival was virtually identical for ABO-incompatible transplants versus matched and center controls (P=0.92 and P=0.60, respectively). Patient survival rates were also similar (P=0.15 and P=0.11, respectively). Early patient survival was lower in ABO-incompatible grafts (P=0.006 vs. matched controls; P=0.001 vs. center controls) because of a higher rate of early infectious death (P=0.037 and P<0.001, respectively). Death-censored graft and patient survival were not significantly affected by induction therapy and anti-CD20 treatment. ABO antibody reduction by column adsorption was associated with similar death-censored graft survival to plasmapheresis.

CONCLUSION

In this analysis of prospectively collected data from a large series of ABO-incompatible living-donor kidney transplants performed at 101 centers, death-censored graft and patient survival rates were similar to those achieved in ABO-compatible control groups over the same period.

One-year protocol biopsies from ABO-incompatible renal allografts compared with a matched cohort of ABO-compatible allografts

Introduction

Early acute antibody-mediated rejection (ABMR) occurs more frequently in ABO-incompatible (ABOi) than in ABO-compatible (ABOc) kidney transplantation. This could lead to increased inflammation/scarring in the ABOi grafts. Protocol biopsy data in ABOi kidney recipients are scarce.

Methods

A single-center retrospective matched cohort study was conducted. Eighty adult living donor (LD) renal transplant recipients without HLA donor-specific antibodies (DSA) transplanted between 2009 and 2012 were included; 20 ABOi and 60 ABOc controls matched for donor age and transplantation year. Protocol biopsies at one yr were scored according to the Banff classification. Three sums of scores were constructed: tubulointerstitial inflammation (t + i = 0 vs. >0), microvascular inflammation (g + ptc = 0 vs. >0), scarring/hyalinosis (ci + ct + cv + ah ≤ 1 vs. >1. Scores and presence of subclinical rejection (SCR) at one yr were compared.

Results

Protocol biopsy findings at one yr in the ABOi vs. ABOc matched control group were not statistically different: (t + i) > 0, 30% vs. 20%; (g + ptc) > 0, 5% vs. 8%; (ci + ct + cv + ah) > 1, 85% vs. 60%, respectively. No transplant glomerulopathy occurred. SCR rate at one yr was 30% vs. 18%, subclinical ABMR 5% vs. 7% (all with de novo HLA DSA).

Conclusion

One-year protocol biopsies of ABOi and ABOc LD recipients do not differ in chronic changes, inflammation, or SCRs.

Antibody-incompatible kidney transplantation in 2015 and beyond

Rejection caused by donor-specific antibodies (principally ABO and HLA antibodies) has become one of the major barriers to successful long-term transplantation. This review focuses on clinical outcomes in antibody-incompatible transplantation, the current state of the science underpinning clinical observations, and how these may be translated into further novel therapies. The clinical outcomes for allografts facing donor-specific antibodies are at present determined largely by the use of agents developed in the 20th century for the treatment of T-lymphocyte-mediated cellular rejection, such as interleukin-2 agents and anti-thymocyte globulin. These treatments are partially effective, because acute antibody-mediated rejection is mediated to a considerable extent by T lymphocytes. However these treatments are essentially ineffective in chronic antibody-mediated rejection. Future therapies for the prevention and treatment of antibody-mediated rejection are likely to fall into the categories of those that reduce antibody production, extracorporeal antibody removal and disruption of the effector arms of antibody-mediated tissue damage.

An update on ABO-incompatible kidney transplantation

ABO-incompatible kidney transplantation is nowadays a well-established procedure to expand living donor transplantation to blood group incompatible donor/recipient constellations. In the last two decades, transplantation protocols evolved to more specific isohaemagglutinin elimination techniques and established competent antirejection protection protocols without the need of splenectomy. ABOi kidney transplantation associated accommodation despite isohaemagglutinin reappearance, C4d positivity of peritubular capillaries as well as the increased incidence of bleeding complications is currently under intense investigation. However, most recent data show excellent graft survival rates equivalent to ABO-compatible kidney transplantation outcome.

Early clinical complications after ABO-incompatible live-donor kidney transplantation: a national study of Medicare-insured recipients

BACKGROUND

Descriptions of the sequelae of ABO-incompatible (ABOi) kidney transplantation are limited to single-center reports, which may lack power to detect important effects.

METHODS

We examined U.S. Renal Data System registry data to study associations of ABOi live-donor kidney transplantation with clinical complications in a national cohort. Among 14,041 Medicare-insured transplants in 2000 to 2007, 119 non-donor-A2 ABOi transplants were identified. A2-incompatible (n=35) transplants were categorized separately. Infection and hemorrhage events were identified by diagnosis codes on billing claims. Associations of ABO incompatibility with complications were assessed by multivariate Cox regression.

RESULTS

Recipients of ABOi transplants experienced significantly (P<0.05) higher incidence of wound infections (12.7% vs. 7.3%), pneumonia (7.6% vs. 3.8%), and urinary tract infections (UTIs) or pyelonephritis (24.5% vs. 15.3%) in the first 90 days compared with ABO-compatible recipients. In adjusted models, ABO incompatibility was associated with twice the risk of pneumonia (adjusted hazard ratio [aHR], 2.22; 95% confidence interval [CI], 1.14-4.33) and 56% higher risk of UTIs or pyelonephritis (aHR, 1.56; 95% CI, 1.05-2.30) in the first 90 posttransplantation days, and 3.5 times the relative risk of wound infections in days 91 to 365 (aHR, 3.55; 95% CI, 1.92-6.57). ABOi recipients, 19% of whom underwent pre- or peritransplant splenectomy, experienced twice the adjusted risk of early hemorrhage (aHR, 1.96; 95% CI, 1.19-3.24). A2-incompatible transplantation was associated only with early risk of UTIs or pyelonephritis.

CONCLUSION

ABOi transplantation offers patients with potential live donors an additional transplant option but with higher risks of infectious and hemorrhagic complications. Awareness of these complications may help improve protocols for the management of ABOi transplantation.

Strategies to increase the donor pool and access to kidney transplantation: an international perspective

In this position article, DESCARTES (Developing Education Science and Care for Renal Transplantation in European States) board members describe the current strategies aimed at expanding living and deceased donor kidney pools. The article focuses on the recent progress in desensitization and kidney paired exchange programmes and on the expanded criteria for the use of donor kidneys and organs from donors after circulatory death. It also highlights differences in policies and practices across different regions with special regard to European Union countries. Living donor kidney paired exchange, the deceased donor Acceptable Mismatch Programme and kidneys from donors after circulatory death are probably the most promising innovations for expanding kidney transplantation in Europe over the coming decade. To maximize success, an effort is needed to standardize transplant strategies, policies and legislation across European countries.

ABO incompatible renal transplants: Good or bad?

ABO incompatible kidney transplantation (ABOi-KT) was previously considered to be an absolute contraindication for patients with end-stage kidney disease (ESKD) due to hyperacute rejection related to blood type barrier. Since the first successful series of ABOi-KT was reported, ABOi-KT is performed increasingly all over the world. ABOi-KT has led to an expanded donor pool and reduced the number of patients with ESKD awaiting deceased kidney transplantation (KT). Intensified immunosuppression and immunological understanding has helped to shape current desensitization protocols. Consequently, in recent years, ABOi-KT outcome is comparable to ABO compatible KT (ABOc-KT). However, many questions still remain unanswered. In ABOi-KT, there is an additional residual immunological risk that may lead to allograft damage, despite using current diverse but usually intensified immunosuppressive protocols at the expense of increasing risk of infection and possibly malignancy. Notably, in ABOi-KT, desensitization and antibody reduction therapies have increased the cost of KT. Reassuringly, there has been an evolution in ABOi-KT leading to a simplification of protocols over the last decade. This review provides an overview of the history, outcome, protocol, advantages and disadvantages in ABOi-KT, and focuses on whether ABOi-KT should be recommended as a therapeutic option of KT in the future.

Tailored desensitization strategies in ABO blood group antibody incompatible renal transplantation

ABO blood group incompatible renal transplantation, using desensitization procedures, is an effective strategy. Efforts have been made to reduce desensitization: these are usually applied to all patients indiscriminately. The Guy's Hospital ABO blood group incompatible desensitization regimen uses a tiered approach, tailoring strategy according to initial antibody titres. Sixty-two ABO blood group incompatible living donor transplant recipients were compared with 167 recipients of blood group compatible living donor renal transplants. There were no statistically significant differences in allograft survival rates at 1 or 3 years post-transplant, rejection in the first year post-transplant or renal function in the first 3 years post-transplant. There was a higher rate of death in ABO blood group incompatible transplant recipients - this could be associated with differences in age and HLA mismatch between the two groups. Four ABO blood group incompatible patients experienced antibody-mediated rejection (no episode was associated with a rise in ABO blood group antibodies). Of the patients who received no desensitization, or rituximab alone, none has experienced antibody mediated rejection or experienced allograft loss. Tailoring the use of desensitization in ABO blood group incompatible renal transplantation according to initial ABO blood group antibody titres led to comparable results to blood group compatible transplantation.

Kidney transplantation across HLA and ABO antibody barriers

PURPOSE OF REVIEW

A significant number of kidney transplantations in industrialized countries is currently performed over human leukocyte antigen (HLA) or ABO antibody barriers after living donation to encounter the increasing shortage of organs from deceased donors. Although patients with moderate titers of anti-A/B antibodies may easily be desensitized with no negative impact on allograft survival, recipients with high titers and HLA sensitized patients demonstrate a substantial risk for antibody-mediated rejection, limiting long-term outcomes.

RECENT FINDINGS

The use of powerful desensitization strategies including plasmapheresis and immunoadsorption, extended therapeutic options such as the application of the recently introduced complement inhibitors, and refined antibody detection techniques may further facilitate transplantations, especially in the HLA-sensitized kidney transplant recipient. On the contrary, special strategies such as the Eurotransplant Acceptable Mismatch Program or kidney paired exchange help improving long-term outcomes in these difficult to transplant patients by circumventing the HLA (or ABO) antibody barrier.

SUMMARY

As compared with waiting for a compatible deceased donor organ, HLA and ABO incompatible transplantations performed in experienced centers have become a reasonable alternative for end-stage kidney disease patients with an incompatible live donor. Whenever possible, however, the transplantation should be performed between ABO compatible donor-recipient pairs in the absence of positive crossmatch results.

ABO-incompatible kidney transplantation

PURPOSE OF REVIEW

A dramatic shortage of available organs around the world encouraged attempts to cross previously forbidden immunological boundaries in kidney transplantation. This review focuses on the recent results of ABO-incompatible kidney transplantation.

RECENT FINDINGS

The outcome of ABO-incompatible kidney transplantation in terms of patient and graft survival is comparable to ABO-compatible transplantation for adult and pediatric recipients. Splenectomy has been replaced by the B-cell-depleting agent rituximab to avoid isoagglutinin titer rebound, prevent antibody-mediated rejection, and improve graft survival. However, the risk for infections may be increased and warrants caution. Corticosteroids remain a necessary component of any ABO-incompatible protocol; early as well as late steroid withdrawal may bear an enhanced risk for acute rejection and should only be performed with careful follow-up including protocol biopsies. The few studies that have long-term outcomes using protocol biopsies have characterized a state of accommodation by up-regulation of complement inhibitors, down-regulation of A/B antigens, and establishment of endothelial chimerism over time.

SUMMARY

The experience accumulated around the world indicates that ABO-incompatible kidney transplantation is well tolerated and effective in adults and in children, and it represents an important step forward in expanding the living donor pool. Further understanding of ABO-incompatible graft accommodation may have broader implication also for human leukocyte antigen-sensitized allograft recipients.

Rituximab in renal transplantation

Rituximab is a chimeric anti-CD20 monoclonal antibody that leads to B cell depletion. It is not licensed for use in renal transplantation but is in widespread use in ABO blood group incompatible transplantation. It is an effective treatment for post-transplant lymphoproliferative disorder, and is also used in both HLA antibody incompatible renal transplantation and the treatment of acute rejection. Recent evidence suggests rituximab may prevent the development of chronic antibody mediated rejection. The mechanisms underlying its effects are likely to relate both to long-term effects on plasma cell development and to the impact on B cell modulation of T cell responses. Rituximab (in multiple doses or in combination with other monoclonal antibodies and/or other immunosuppressants) may lead to an increase in infectious complications, although the evidence is not clear. Rarely, the drug can cause a cytokine release syndrome, thrombocytopenia and neutropenia. It has been related to an increased risk of progressive multifocal leucoencephalopathy and, recently, deaths from cardiovascular causes. Trials examining the effects of rituximab in induction therapy for compatible renal transplantation and the treatment of chronic antibody mediated rejection are ongoing. These trials should aid greater understanding of the role of B-cells in the alloresponse to renal transplantation.

Bleeding complications in pediatric ABO-incompatible kidney transplantation

BACKGROUND

ABO-incompatible renal transplantation (ABOi-RTx) following preconditioning with immunoadsorption (IA) and rituximab is a promising approach to facilitate living-related RTx. However, clinical experience is limited in pediatric patients.

METHODS

Three patients underwent living-related ABOi-RTx in our center. Preoperative IA was performed six, ten and 11 times in patient one, two and three, respectively, to achieve isoagglutinin titers of ≤1:8 on the day of transplantation; rituximab was administered once. The immunosuppressive regimen further comprised tacrolimus, mycophenolate, methylprednisolone and basiliximab; immunoglobulin G (IgG) was infused on the day of ABOi-RTx.

RESULTS

All three patients achieved normal renal function within 2-6 days post-RTx. Major postoperative bleeding occurred in two patients, with one requiring repeated blood transfusions and the other a surgical revision 4 h after RTx, despite local citrate anticoagulation use during the preoperative IA procedures in the latter patient. A pyelonephritis-associated increase of the isoagglutinin IgG/IgM titers to 1:64/1:128 led to a biopsy-proven acute humoral rejection in the third patient, which was treated successfully with plasma exchange and methylprednisolone pulses. The estimated glomerular filtration rate at 18, 8 and 23 months post-RTx was 96, 52 and 74 ml/min/1.73 m(2), respectively.

CONCLUSIONS

ABOi-RTx can successfully be performed in pediatric patients after preconditioning with quadruple immunosuppression, rituximab and IA. Caution is required regarding bleeding complications, which are most likely due to the unspecific binding of coagulation factors during repeated IA.