Japan's experience with living-donor kidney transplantation across ABO barriers

Comparison of early and late Pneumocystis jirovecii Pneumonia in kidney transplant patients: the Korean Organ Transplantation Registry (KOTRY) Study

Late Pneumocystis jirovecii pneumonia (PJP) is not rare in the era of universal prophylaxis after kidney transplantation. We aimed to determine the nationwide status of PJP prophylaxis in Korea and compare the incidence, risk factors, and outcomes of early and late PJP using data from the Korean Organ Transplantation Registry (KOTRY), a nationwide Korean transplant cohort. We conducted a retrospective analysis using data of 4,839 kidney transplant patients from KOTRY between 2014 and 2018, excluding patients who received multi-organ transplantation or were under 18 years old. Cox regression analysis was performed to determine risk factors for early and late PJP. A total of 50 patients developed PJP. The number of patients who developed PJP was same between onset before 6 months and onsets after 6 months. There were no differences in the rate, duration, or dose of PJP prophylaxis between early and late PJP. Desensitization, higher tacrolimus dose at discharge, and acute rejection were associated with early PJP. In late PJP, old age as well as acute rejection were significant risk factors. In conclusion late PJP is as common and risky as early PJP and requires individualized risk-based prophylaxis, such as prolonged prophylaxis for old patients with a history of rejection.

Peripheral blood transcriptome analysis and development of classification model for diagnosing antibody-mediated rejection vs accommodation in ABO-incompatible kidney transplant

The major obstacle to successful ABO blood group-incompatible kidney transplantation (ABOi KT) is antibody-mediated rejection (AMR). This study aimed to investigate transcriptional profiles through RNA sequencing and develop a minimally invasive diagnostic tool for discrimination between accommodation and early acute AMR in ABOi KT. Twenty-eight ABOi KT patients were selected: 18 with accommodation and 10 with acute AMR at the 10th day posttransplant protocol biopsy. Complete transcriptomes of their peripheral blood were analyzed by RNA sequencing. Candidate genes were selected by bioinformatics analysis, validated with quantitative polymerase chain reaction, and used to develop a classification model to diagnose accommodation. A total of 1385 genes were differentially expressed in accommodation compared with in AMR with P-adjusted < .05. Functional annotation and gene set enrichment analysis identified several immune-related and immunometabolic pathways. A 5-gene classification model including COX7A2L, CD69, CD14, CFD, and FOXJ3 was developed by logistic regression analysis. The model was further validated with an independent cohort and discriminated between accommodation and AMR with 92.7% sensitivity, 85.7% specificity, and 91.7% accuracy. Our study suggests that a classification model based on peripheral blood transcriptomics may allow minimally invasive diagnosis of acute AMR vs accommodation and subsequent patient-tailored immunosuppression in ABOi KT.

Clinical outcomes of ABO- and HLA-incompatible kidney transplantation: a nationwide cohort study

This was a nationwide cohort study to investigate the impact of anti-A/B and donor-specific anti-HLA (HLA-DSA) antibodies on the clinical outcomes in kidney transplant recipients (KTRs). We classified a total of 1964 KTRs into four groups: transplants from ABO-incompatible donors (ABOi, n = 248); transplants in recipients with HLA-DSA (HLAi, n = 144); transplants from combined ABOi and HLAi donors (ABOi + HLAi, n = 31); and a control group for whom neither ABOi nor HLAi was applicable (CONT, n = 1541). We compared the incidence of biopsy-proven acute rejection (BPAR), allograft and patient survival rates. The incidence of BPAR was higher in the HLAi and ABOi + HLAi groups relative to the CONT group; in contrast, it was not higher in the ABOi group. Death-censored graft survival rates did not differ across the four groups. However, relative to the CONT group, patient survival rate was reduced in the ABOi and ABOi + HLAi groups, and with infection being the most common cause of death. Further, multivariable analysis revealed that desensitization therapy because of ABOi or HLAi was independent risk factors for patient mortality. HLAi was a more important risk factor for BPAR compared with ABOi. However, pretransplant desensitization therapy for either ABOi or HLAi significantly increased the risk of infection-related mortality.

Therapeutic Apheresis in Immunologic Renal and Neurological Diseases

Since the mid 1970s, when membrane modules became available, plasma separation techniques have gained in importance especially in the past few years. The advantages of this method are a complete separation of the corpuscular components from the plasma and due to increased blood flow rate and higher efficacy. Systemic autoimmune diseases based on an immune pathogenesis produce autoantibodies and circulating immune complexes, which cause inflammation in the tissues of various organs. In most cases, these diseases have a poor prognosis without treatment. Therapeutic apheresis (TA) in combination with immunosuppressive therapies has led to a steady increase in survival rates over the last 40 years. The updated information on immunology and molecular biology of different immunologic diseases are discussed in relation to the rationale for apheresis therapy and its place in combination with other modern treatments. The different diseases can be treated by various apheresis methods such as therapeutic plasma exchange (TPE) with substitution solution, or with online plasma or blood purification using adsorption columns, which contain biological or non-biological agents. Here, the authors provide an overview of the most important pathogenic aspects indicating that TA can be a supportive therapy in systemic autoimmune diseases such as renal and neurological disorders. For the immunological diseases that can be treated with TA, the guidelines of the German Working Group of Clinical Nephrology and of the Apheresis Committee of the American Society for Apheresis are cited.

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.

Application of flow cytometry to measure anti-A/B antibody in ABO-incompatible kidney transplantation

BACKGROUND

The aim of this study was to compare anti-ABO antibody levels as measured by means of flow cytometry (FCM) with the levels measured with the use of the column agglutination test (CAT), and to evaluate the clinical outcome as it relates to the baseline mean fluorescence intensity (MFI) ratio obtained by FCM.

METHODS

We reviewed 21 cases of ABO-incompatible kidney transplantation (ABO-i KT). In these patients, baseline IgG titers were measured with the use of both FCM and CAT methods. We investigated the correlation between levels measured by FCM and those by CAT with the use of correlation coefficients. Patients were classified into a high MFI ratio group (≥200; n = 7) or low MFI ratio group (<200; n = 14).

RESULTS

The MFI ratio for the FCM-based method was highly correlated with the titer measured by CAT (r = 0.890; P = .01). The relationship between MFI ratio and CAT titer can be expressed as follows: log (MFI ratio) = 0.879 × log (CAT titer) + 0.298. The number of pre-transplantation rounds of plasmapheresis significantly increased as the baseline MFI ratio increased. The allograft function was immediately recovered and stable. A single case of acute cellular rejection was observed in the low MFI ratio group.

CONCLUSIONS

Anti-ABO antibody levels measured by means of the FCM-based method were highly correlated with the levels measured with the use of CAT in cases of ABO-i KT. The decreased level of anti-ABO antibody measured by means of FCM after plasmapheresis suggests its potential as an effective and objective method for assessment of anti-ABO antibody levels.

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.

Outcome of single pediatric deceased donor renal transplantation to adult kidney transplant recipients

INTRODUCTION

In times of organ shortage more kidneys were transplanted in 'expanded criteria kidney' programs. This study examines the outcome of adult kidney recipients from pediatric donors.

MATERIALS AND METHODS

This single-center retrospective analysis evaluated eight adult patients who received a kidney from a deceased pediatric donor (age 5-17) between 06/2000 and 09/2011.

RESULTS

The median donor age was 14 years (range 5-17). The median recipient age was 49 years (range 25-57). The median cold ischemia time was 13.3 h (range 4.3-20.1), while the median warm ischemia time was 53 min (range 42-60). The median follow-up was 35.8 months (range 7-142). Acute rejection was observed in 50.0% of cases. The median HLA mismatch was 2.0. The median 1-year creatinine level was 0.95 mg/dl, the uncensored 1-year graft survival was 75.0% and the 3-year graft survival 62.5%, respectively. No recipient died within the follow-up period. As severe surgical complications, one stenosis of the renal artery and one lymphocele needing surgical revision were observed.

CONCLUSIONS

Renal transplantation of a deceased single pediatric donor to an adult recipient can be performed safely and shows a good outcome. Wherever feasible, single pediatric kidney transplantation can double the number of recipients over an 'en-bloc' transplantation. The price for a single pediatric kidney transplant may be a higher vascular complication rate and a higher rejection risk. Despite the higher risks, transplantation of a single pediatric donor kidney should be performed when accomplishable.

Impact of the baseline anti-A/B antibody titer on the clinical outcome in ABO-incompatible kidney transplantation

BACKGROUND/AIMS

We investigated the impact of the baseline anti-A/B antibody titer on the clinical outcome in ABO-incompatible kidney transplantation (IKT).

METHODS

We included 183 patients who had undergone KT (40 ABO IKT and 143 ABO-compatible KT). Eight patients with a baseline titer of ≥1:512 were assigned to the high-titer group and 32 patients with a baseline titer of ≤1:256 were assigned to the low-titer group. Patients who underwent ABO-compatible KT were used as the control group. We compared the clinical outcomes of the three groups.

RESULTS

Before transplantation, the high-titer group displayed more frequent antibody rebound, as shown in a lower titer reduction rate, and more difficulty reaching the target titer (1:16) than the low-titer group. During the postoperative period and out-clinic follow-up, antibody rebound was more frequent, and the rate of acute rejection and infection were significantly higher and allograft function was lower in the high-titer group than in the low-titer and control groups. Multivariate analysis showed that high baseline antibody titer was an independent risk factor for acute rejection.

CONCLUSION

ABO IKT in the high-titer group (baseline titer ≥1:512) required greater caution compared to the low-titer group because of the higher tendency of antibody rebound and the risk for acute rejection.

Combined use of rituximab and plasmapheresis pre-transplant increases post-transplant infections in renal transplant recipients with basiliximab induction therapy

INTRODUCTION

We investigated the effect of combined use of rituximab (RTX) and plasmapheresis (PP) pre-transplant on post-transplant infection.

METHODS

A total of 196 patients undergoing living-donor kidney transplantation at Seoul St. Mary's Hospital, all of whom underwent basiliximab induction therapy, were included in the study. They were divided into 3 groups: RTX/PP/intravenous immune globulin (IVIG) (the RPI group; n = 53), RTX monotherapy (the RTX group; n = 14), and control (the CONT group; n = 129). We compared the post-transplant infections in the 3 groups.

RESULTS

The overall prevalence of infection was significantly higher, and the infection-free survival rate was lower, in the RPI group compared with the RTX or CONT groups (P < 0.05). A trend toward more severe bacterial infections was seen in the RPI group compared with the other groups, and fungal infections developed only in the RPI group. After anti-rejection therapy, a significantly higher rate of infection developed in the RPI group than in the other groups (P < 0.05). In addition, the RPI group was an independent risk factor for the development of infection.

CONCLUSION

Our results show that in the setting of basiliximab induction, the use of combined RTX and PP therapy pre-transplant significantly increases the risk for post-transplant infection.

B-cell regulation and its application to transplantation

There has been increasing interest in the role played by B cells and their associated antibody in the immune response to an allograft, driven by the need to undertake antibody-incompatible transplantation and evidence suggesting that B cells play a role in acute T-cell-mediated rejection and in acute and chronic antibody-mediated rejection. This review focuses on the molecular events, both activating and inhibitory, which control B-cell activation, and considers how this information might inform therapeutic strategies. Potential targets include the BAFF (B-cell-activating factor belonging to the tumour necrosis factor family) and CD40-CD40L pathways and inhibitory molecules, such as CD22 and FcγRIIB. B cells can also play an immunomodulatory role via interleukin (IL)10 production and may contribute to transplant tolerance. The expansion of allograft-specific IL10-producing B cells may be an additional therapeutic goal. Thus, the treatment paradigm required in transplantation has shifted from that of simple B-cell depletion, to that of a more subtle, differential manipulation of different B-cell subsets.

Current topics in therapeutic plasmapheresis

Therapeutic plasmapheresis has been used for intractable diseases that cannot be cured by conventional drug therapy. Currently, the use of therapeutic plasmapheresis has been approved for 27 diseases by Japan's National Health Insurance system and is mainly categorized into three modalities: plasma exchange (PE), double-filtration plasmapheresis (DFPP), and plasma adsorption (PA). Plasma separators and/or fractionators are essential for the therapy. PE is performed for two purposes: removal of pathogenic antigens or substances in the plasma fraction and supplementation of essential factors, such as albumin and coagulation factors. PE can be used for thrombotic microangiopathy and acute hepatic failure. DFPP can be performed for selective removal of macromolecules while avoiding the use of substitution fluid (i.e., albumin or fresh frozen plasma). DFPP has now been used for conditions involving relatively larger plasma molecules, including hyperviscosity syndrome and ABO-incompatible kidney transplantation. PA can specifically remove pathogenic agents, such as low-density lipoprotein or autoantibodies, in the IgG fractions by the adsorption column and does not require substitution fluids. PA has now been used for a wide variety of neurological diseases, including chronic inflammatory demyelinating polyneuropathy. This review describes the characteristics of each modality, seeking to improve the efficacy and specificity of removal of the target substance.

Desensitization with antigen-specific immunoadsorption interferes with complement in ABO-incompatible kidney transplantation

BACKGROUND

Complement activation was characterized during and after desensitization treatment in 19 consecutive patients receiving ABO-incompatible (ABOi) living donor kidney transplants to assess the effect of desensitization protocol including antigen-specific immunoadsorption (IA) on complement activation.

METHODS

All patients received rituximab- and tacrolimus-based triple treatment. Anti-A/B antibodies were removed by IA. Serial determinations of C3, C3a, the C3a/C3 ratio, and sC5b-9 were carried out between day -30 and postoperative day 30. C1q was measured on day -30 and the day before the transplantation. In two recipients, eluates from immunoadsorbent columns were analyzed for C3a, C1q, and immunoglobulins by western blotting. Same complement analysis was performed in eluate from a control column after in vitro perfusion of AB-plasma.

RESULTS

Patient and graft survival were 100% for a median follow-up of 40 months (range, 12-60 months). There were no humoral rejections based on ABO-antigen-antibody interactions. C3a and the C3a/C3 ratio declined with the start of IA treatment, and this decline was maintained postoperatively. C1q declined from day -30 to a lower value on the day before transplantation (P<0.05). In eluates from both patient and control, immunoadsorbent column immunoglobulins together with C3a and C1q were detected.

CONCLUSIONS

The current protocol including antigen-specific IA interferes with the complement system; this effect may be partially responsible for the absence of humoral rejection resulting from ABO-antigen-antibody interactions and the excellent outcomes obtained after ABO-incompatible kidney transplantation.

Therapeutic apheresis for renal disorders

This review summarizes the clinical evidence and practical details for the use of plasmapheresis and other apheresis modalities for each indication in nephrology. Updated information on the molecular biology and immunology of each renal disease is discussed in relation to the rationale for apheresis therapy and its place amid other available treatments. Autoantibody-mediated diseases, such as anti-GBM (anti-glomerular basement membrane) glomerulonephritis (GN), ANCA (antineutrophil cytoplasmic antibody)-related GN and the antibody-mediated type of TTP (thrombotic thrombocytopenic purpura), and alloantibody-mediated diseases such as kidney transplant sensitization and humoral rejection, can be treated by various plasmapheresis methods. These include standard plasmapheresis with a replacement volume, or plasmapheresis with online plasma purification using adsorption columns or secondary filtration. However, it should be noted that the pathogenic molecules implicated in FSGS (focal segmental glomerulosclerosis), myeloma cast nephropathy, and perhaps other diseases are too small to be removed by most online purification methods. A great majority of controlled trials and series on which evidence-based treatment recommendations are made were performed using centrifugal plasmapheresis; it is presumed that membrane-separation plasmapheresis is equally efficacious. For some rarer diseases, such as MPGN (membranoproliferative GN) type 2 with factor H abnormalities or C3Nef (C3 nephritic factor) autoantibodies, there are only a few case reports, but enough scientific understanding to warrant a trial of plasmapheresis in severe cases. Photopheresis, which is effective for cell-mediated rejection in heart and lung transplantation, has not yet found a place in the routine treatment of kidney transplant rejection.

ABO-incompatible kidney transplantation using regenerative selective immunoglobulin adsorption

BACKGROUND

ABO-incompatible (ABOi) kidney transplantation is an established procedure relying on the removal of donor-specific isoagglutinine antibodies as part of the recipient preconditioning. At present, current protocols using immunoadsorption apply a single-use selective carbohydrate isoagglutinine adsorber. A regenerative and selective immunoglobulin immunoadsorption could be an alternative but has not been reported for ABOi transplantation.

METHODS

Eight patients were treated with the commonly used isoagglutinine carbohydrate epitope adsorber and seven with a regenerative polyclonal sheep anti-immunoglobulin adsorber as part of the preconditioning for ABOi kidney transplantation. An IgG-isoagglutinine titer of less or equal 1:4 qualified for transplantation. Treatment safety, efficiency, length of desensitization, number of postoperative immunoadsorptions, and allograft outcome were retrospectively compared.

RESULTS

With the use of the immunoglobulin adsorber the median initial isoagglutinine IgG titers of 1:64 (range 1:32-1:256) were lowered to the target of 1:4 preoperatively with a mean of 6.2 immunoadsorptions (range 5-11). Mean IgG/IgM titer step reduction per IA was 1.98/1.21 for (range 0-4/0-4) and mean titer step rebound 1.31/0.82 (range 0-4/0-3), respectively. The number of immunoadsorptions and length of desensitization was not different from the use of the specific isoagglutinine adsorbers. After transplantation, no rejection occurred and only one postoperative immunoadsorption was necessary. No adverse events in relation to immunoadsorption were observed. Graft function was comparable to the isoagglutinine adsorber group.

CONCLUSION

These data suggest that ABOi kidney transplantation can be performed safely and effectively with a selective regenerative immunoglobulin immunoadsorber.

ABO-incompatible renal transplantation: From saline flushes to antigen-specific immunoadsorption-Tools to overcome the barrier

On April 23, 1951, a 30-year-old woman received the first intentional ABOi (ABO incompatible) renal transplantation in Boston. At that time, it was commonly believed that intensely rinsing the graft to remove blood would be sufficient to overcome any immunological problems associated with blood type incompatibility. However, when the abovementioned patient and another ABOi transplant recipient died within a month, Humes and colleagues arrived at the same conclusion: "We do not feel that renal transplantation in the presence of blood incompatibility is wise." In the decades that followed, we learned that the oligosaccharide surface antigens representing the ABO-blood group antigens are expressed not only on erythrocytes but also on cells from various tissues, including the vascular endothelium. The growing gap between organ demand and availability has sparked efforts to overcome the ABO barrier. After its disappointing results in the early 1970s, Japan became the leader of this endeavor in the 1980s. All protocols are based on 2 strategies: removal of preformed antibodies with extracorporeal techniques and inhibition of ongoing antibody production. Successful ABOi renal transplantation became possible with the advent of splenectomy, new immunosuppressive drugs (e.g., rituximab, a monoclonal antibody against CD20), and extracorporeal methods such as antigen-specific immunoadsorption. This review summarizes the underlying pathophysiology of ABOi transplantation and the different protocols available. Further, we briefly touch potential short- and long-term problems, particularly the incidence of infectious complications and malignancies, that can arise with high-intensity immunosuppressive therapy.

Analysis of the Results of ABO-Incompatible Kidney Transplantation: In Comparison with ABO-Compatible Kidney Transplantation

Purpose

The number of patients waiting for kidney transplantation is incessantly increasing, but the number of cadaveric kidney transplantations or ABO-compatible donors is so insufficient that ABO-incompatible kidney transplantation is being performed as an alternative. There are overseas studies and research showing that the 5-year survival rate and 5-year graft survival rate of ABO-incompatible kidney transplantation are not much different from those of ABO-compatible kidney transplantation. However, domestic research on the subject is rare. Therefore, we report the results of 22 ABO-incompatible kidney transplantation cases performed in our hospital.

Materials and Methods

This research was from 22 patients in our hospital who underwent ABO-incompatible kidney transplantation from 15 February 2007 to 20 May 2010.

Results

As yet, there have been no donor graft losses and no deaths after transplantation. The results of the two groups were analyzed by analysis of covariance of the creatinine value of the recipients at 6 months after the operation, corrected for the preoperative value in order to statistically identify whether there were differences in renal function after the operation between ABO-compatible and ABO-incompatible kidney transplantation. The results of the analysis of covariance showed no statistical difference in renal function after the operation between the two groups.

Conclusions

Even though there were not many cases, our initial results for ABO-incompatible kidney transplantation were positive. Considering the increasing number of patients waiting for kidney transplantation, longer-term domestic research studies of ABO-incompatible kidney transplantation are necessary.

Changing donor source pattern for kidney transplantation over 40 years: a single-center experience

BACKGROUND/AIMS

Kidney transplantations at our center rely mainly on living donors. The purpose of this study was to suggest future donor supply directions by reviewing changing trends in donor type.

METHODS

During the past 40 years, 1,690 kidney transplantations were performed at our center. We divided the follow-up period into four decades and the donor population into three groups: living related, living unrelated, and deceased. We analyzed changing trends in donors from each group for each decade. Patients receiving overseas transplantation were also included.

RESULTS

The proportion of living related donors decreased from 84% (54/64) in the 1970s to 61% (281/458) in the 2000s. Living unrelated donors showed a sustained proportion of around 20% after 1990. However, among living unrelated donors, the proportion of spouse donors increased from 4.6% (17/369) in the 1980s to 8.5% (39/458) in the 2000s. Transplants from deceased donors were only 3.3% (12/369) in the 1980s. However the proportion of deceased donors increased gradually, reaching 13.2% (105/799) in the 1990s and 19.9% (91/458) after 2000. Overseas transplantations increased after 2000 and reached 20% of all cases treated in our center during the 2000s. Such transplantations peaked in 2006 and decreased markedly thereafter.

CONCLUSIONS

The proportion of each donor type has continuously changed, and the changes were associated with changes in the social structure and system. We expect that this study could be an important reference for other countries to estimate future changes of donor type.

Exchange living donor liver transplantation to overcome ABO incompatibility in adult patients

ABO incompatibility is the most common cause of donor rejection during the initial screening of adult patients with end-stage liver disease for living donor liver transplantation (LDLT). A paired donor exchange program was initiated to cope with this problem without ABO-incompatible LDLT. We present our results from the first 6 years of this exchange adult LDLT program. Between July 2003 and June 2009, 1351 adult LDLT procedures, including 16 donor exchanges and 7 ABO-incompatible LDLT procedures, were performed at our institution. Initial donor-recipient ABO incompatibilities included 6 A to B incompatibilities, 6 B to A incompatibilities, 1 A to O incompatibility, 1 A+O (dual graft) to B incompatibility, 1 O to AB incompatibility, and 1 O to A incompatibility. Fourteen matches (87.5%) were ABO-incompatible, but 2 (12.5%) were initially ABO-compatible. All ABO-incompatible donors were directly related to their recipients, but 2 compatible donors were each undirected and unrelated directed. After donor reassignment through paired exchange (n = 7) or domino pairing (n = 1), the donor-recipient ABO status changed to A to A in 6, B to B in 6, O to O in 1, A to AB in 1, A+O to A in 1, and O to B in 1, and this made all matches ABO-identical (n = 13) or ABO-compatible (n = 3). Two pairs of LDLT operations were performed simultaneously on an elective basis in 12 and on an emergency basis in 4. All donors recovered uneventfully. Fifteen of the 16 recipients survived, but 1 died after 54 days. In conclusion, an exchange donor program for adult LDLT appears to be a feasible modality for overcoming donor-recipient ABO incompatibility.

Preemptive CD20+ B cell depletion attenuates cardiac allograft vasculopathy in cyclosporine-treated monkeys

Chronic rejection currently limits the long-term efficacy of clinical transplantation. Although B cells have recently been shown to play a pivotal role in the induction of alloimmunity and are being targeted in other transplant contexts, the efficacy of preemptive B cell depletion to modulate alloimmunity or attenuate cardiac allograft vasculopathy (CAV) (classic chronic rejection lesions found in transplanted hearts) in a translational model has not previously been described. We report here that the CD20-specific antibody (alphaCD20) rituximab depleted CD20+ B cells in peripheral blood, secondary lymphoid organs, and the graft in cynomolgus monkey recipients of heterotopic cardiac allografts. Furthermore, CD20+ B cell depletion therapy combined with the calcineurin inhibitor cyclosporine A (CsA) prolonged median primary graft survival relative to treatment with alphaCD20 or CsA alone. In animals treated with both alphaCD20 and CsA that achieved efficient B cell depletion, alloantibody production was substantially inhibited and the CAV severity score was markedly reduced. We conclude therefore that efficient preemptive depletion of CD20+ B cells is effective in a preclinical model to modulate pathogenic alloimmunity and to attenuate chronic rejection when used in conjunction with a conventional clinical immunosuppressant. This study suggests that use of this treatment combination may improve the efficacy of transplantation in the clinic.

Induction of tolerance in renal transplantation using splenic transplantation: experimental study in a canine model

OBJECTIVE

To evaluate in a canine model the induction of tolerance to renal transplantation after splenectomy and splenosis.

MATERIALS AND METHODS

This prospective, experimental, comparative, longitudinal study included 4 experimental groups, each comprising 4 dogs. Group 1 (control group) underwent renal transplantation only; group 2 underwent renal transplantation and splenectomy; group 3 underwent renal transplantation and splenosis; and group 4 underwent renal transplantation, splenectomy, and splenosis. Survival and degree of rejection were compared between the 4 groups.

RESULTS

Splenosis improved renal function after transplantation, as indicated by increased serum creatinine concentration (group 3, 6.2 mg/dL vs group 1, 12.9 mg/dL). Comparison of weighted survival curves (corrected for degree of rejection) demonstrated a significant difference between group 2 (66.0 days) and group 4 (66.2 days) vs group 1 (52.7 days) and group 3 (41.2 days) (P = .05, Wilcoxon rank sum test).

CONCLUSION

These results suggest that in this experimental model of renal transplantation, splenosis and splenectomy induce clinical tolerance, as indicated by improved renal function and prolonged recipient survival.

[Extending the donor pool in renal transplantation]

The number of patients on the renal transplant waiting list has remained constantly high. In this article we highlight two strategies to extend the donor pool and focus on AB0 incompatible and cross-over renal transplantation. Increased immunologic knowledge and improved therapeutic management have facilitated successful AB0 incompatible renal transplantation with very good long-term results. However, this method has only been applied in very few German transplant centers and should be explored further. The term cross-over transplantation implies the exchange of organs between two otherwise incompatible couples enabling compatible transplantation in both couples. The German transplantation law allows only living transplantation in emotionally related couples. However, in specific cases of close interpersonal relationships cross-over transplantation between two couples is acceptable.