Accommodation in abo-incompatible kidney transplantation: why do kidney grafts survive?

Hyporesponsiveness against donor's ABO antigens of renal grafts after ABO-incompatible kidney transplantation

BACKGROUND

ABO antigens expressed on the red blood cells (RBCs) are not identical to those expressed on the renal endothelial cells. The isohemagglutinin assay employing the RBCs is the gold standard for evaluating anti-ABO antibody (Ab) levels. However, it remains unclear whether the anti-ABO Abs detected by the isohemagglutinin assay after ABO-incompatible (ABOi) kidney transplantations (KTx) that are not associated with antibody-mediated rejection can bind to renal graft endothelial cells.

METHODS

Ninety plasma samples were collected from patients with stable graft function after ABO-compatible (ABOc) or ABOi KTx. Anti-ABO Ab titers were examined by both the isohemagglutinin assay and the CD31-ABO microarray, which was developed as a mimic of the ABO antigens expressed on the renal endothelial cells.

RESULTS

The antibody titers detected by the isohemagglutinin assay and the CD31-ABO microarray after the ABOc KTx relatively correlated with each other. However, the CD31-ABO microarray results showed low antibody levels against donor blood group antigens after ABOi KTx and did not correlate with the isohemagglutinin assay. In contrast, the antibody levels against non-donor blood group antigens after ABOi KTx were comparable to those after the ABOc KTx. Fourteen patients received graft biopsies, and no antibody-mediated rejection was observed in ABOi KTx recipients, except for two patients who had anti-donor-HLA Abs.

CONCLUSION

The present study suggested that the anti-ABO Abs detected by the isohemagglutinin assay after ABOi KTx with stable graft function were hyporeactive to the ABO antigen of graft renal endothelial cells.

Usefulness of Thiel-Embalmed Cadavers for Training in Organ Procurement

BACKGROUND

The number of brain-dead donors has been increasing; however, the opportunity for young surgeons to experience deceased donor surgeries is extremely limited, especially in many Asian countries including Japan. Deceased donor surgeries require unique surgical skills and knowledge; however, it is difficult to provide on-the-job guidance and education. Therefore, cadaver training is meaningful and suitable for the training of deceased donor surgeries. Thiel's embalming method (TEM) provides natural coloration, flexibility, and tissue plasticity, and is widely used for cadaver surgical training. In this study, we evaluated the usefulness of Thiel's embalmed cadaver training for organ procurement surgery.

MATERIAL AND METHODS

Each trainee performed hepatectomy, pancreatectomy, and nephrectomy using conventional open techniques. Faculty experts of transplantation surgery and organ procurement took attendees through surgical steps. After the procedure, all participants were asked to complete a voluntary, anonymous survey, consisting of a 10-point satisfaction scale, to evaluate their perceptions of the training.

RESULTS

A total of 33 gastrointestinal surgeons participated in the training program for procuring the liver, pancreas, and kidneys. In the questionnaire administered to the participants, the evaluation was generally satisfactory, with an average of 9.1 points on the 10-point scales. Some participants expressed that Thiel-embalmed cadavers are more suitable for training on organ procurement compared with animals used in wet-lab training.

CONCLUSION

We conclude that organ procurement training in human cadavers preserved by TEM is useful and suitable for practicing deceased donor organ procurement, especially in countries where deceased donors are not common, as in Japan.

Effect of Donor and Recipient ABH-Secretor Status on ABO-Incompatible Living Donor Kidney Transplantation

Introduction

ABO blood group antigens within grafts are continuously exposed to anti-A/B antibodies in the serum of recipients after ABO-incompatible (ABOi) kidney transplantation and are instrumental in antibody-mediated rejection. Some individuals secrete soluble blood group antigens into body fluids. In this study, we investigated the effect of donor and recipient secretor status on the outcomes of ABOi kidney transplantation.

Methods

Data of a total of 32 patients with ABOi living donor kidney transplantation were retrospectively collected between 2014 and 2020 in West China Hospital. The genotype and phenotype of both donors and recipients were examined and evaluated with post-transplantation anti-A/B titer changes, graft function, and rejection.

Results

Of the 32 recipients and 32 donors, 23 (71.9%) recipients and 27 (84.4%) donors had secretor genotypes, whereas 9 (28.1%) recipients and 5 (15.6%) donors did not. Anti-A/B titers after ABOi kidney transplantation were not significantly influenced by the secretor status of either donors or recipients. The post-transplantation serum creatinine (Scr) levels and estimated glomerular filtration rate (eGFR) was better in weak- or non-secretor recipients at day 30 (Scr P = 0.047, eGFR P = 0.008), day 90 (Scr P = 0.010, eGFR P = 0.005), and month 9 (eGFR P = 0.008), and recipients from secretor donors had a lower incidence of graft rejection in the first year after ABOi transplantation (P = 0.004).

Conclusions

A weak secretor status phenotype was found in both genotypes, i.e., individuals who secreted soluble antigens as well as those who did not. The recipient ABH-secretor status may have an influence on early posttransplant renal function, and the donor ABH-secretor status might affect the incidence of graft rejection.

The effect of desensitization therapy in kidney transplantation

BACKGROUND

Desensitization therapy may enable the patient to get allograft in sensitized recipient or solve the organ shortage in ABO-incompatible relationship in kidney transplantation (KT). However, the graft outcome and morbidity remains unclear.

METHODS

We retrospectively analyzed 845 KT patients from January 2010 to February 2016 at Seoul National University Hospital. The patients were divided into three groups as follows: HLA-incompatible (HLAi) group, ABO-incompatible (ABOi) group, and control group. The HLAi group comprised patients who received desensitization therapy due to the presence of donor-specific antibodies (DSAs) or high panel reactive antibodies (PRAs). The ABOi group is defined as those undergoing preoperative desensitization therapy for anti-ABO antibodies.

RESULTS

Of the total of 845 recipients, 48 (5.6%) were HLAi KTs and 71 (13.9%) were ABOi KTs, respectively. Pre-emptive KT is done more frequently in ABOi group, therefore, they had shorter dialysis duration than the others. HLAi recipients had a higher proportion of women than the ABOi group and a higher proportion of re-transplantation. During the 38.4 (0.4-76.9) months of follow-up, there were more acute antibody-mediated rejections (AAMRs) in the HLAi (6.7%) and ABOi (8.5%) groups than in the control group (1.9%) (P = 0.001). However, there was no difference in graft survival, patient survival, and annual allograft among three groups.

CONCLUSIONS

Despite the higher incidence of AAMRs, HLAi and ABOi KTs showed a favorable graft and patient outcome after desensitization therapy.

Effects of Neutralization by Soluble ABH Antigens Produced by Transplanted Kidneys From ABO-Incompatible Secretor Donors

BACKGROUND

Grafts survive despite blood group antigens on the transplant being continuously exposed to antibodies in the blood of recipients in ABO-incompatible kidney transplantation (ABOi KT), owing to the mechanism of accommodation. We analyzed the immunodynamics of soluble ABH antigens in allografts from secretor donors and the influence of such immunodynamics on accommodation and subsequent graft survival in ABOi KT.

METHODS

The genotype of a known human β-galactoside α-1,2-fucosyltransferase gene (FUT2), which determines soluble ABH antigen secretor status, was established in 32 donors for ABOi KT at the Severance Hospital, from June 2010 to July 2015. Clinical outcomes of recipients, such as anti-A/B antibody titer change, renal function, and graft survival, were evaluated.

RESULTS

Twenty-five donors were secretors (78.1%), and seven were nonsecretors (21.9%). The frequency of anti-A/B IgG or IgM antibody titer elevation or reduction post-transplantation was not significantly related to donor secretor status. However, IgM titer was rapidly reduced in recipients transplanted from nonsecretor donors (P=0.01), which could be explained by the lack of absorption effect of soluble antigens, enhancing the binding of antibodies to antigens in the allografts. Interestingly, soluble ABH antigens did not affect rejection-free graft survival, which may be due to the nature of β-galactoside α-1,2-fucosyltransferase.

CONCLUSIONS

Soluble ABH antigens produced by transplanted kidneys from secretor donors played a role in inducing accommodation within three months of KT through neutralization; however, major graft outcomes were not affected.

Acquired Downregulation of Donor-Specific Antibody Production After ABO-Incompatible Kidney Transplantation

The mechanism of long-term B cell immunity against donor blood group antigens in recipients who undergo ABO-incompatible (ABOi) living-donor kidney transplantation (LKTx) is unknown. To address this question, we evaluated serial anti-A and anti-B antibody titers in 50 adult recipients. Donor-specific antibody titers remained low (≤1:4) in 42 recipients (84%). However, antibodies against nondonor blood group antigens were continuously produced in recipients with blood type O. We stimulated recipients' peripheral blood mononuclear cells in vitro to investigate whether B cells produced antibodies against donor blood group antigens in the absence of graft adsorption in vivo. Antibodies in cell culture supernatant were measured using specific enzyme-linked immunosorbent assays (ELISAs). Thirty-five healthy volunteers and 57 recipients who underwent ABO-compatible LKTx served as controls. Antibody production in vitro against donor blood group antigens by cells from ABOi LKTx patients was lower than in the control groups. Immunoglobulin deposits were undetectable in biopsies of grafts of eight recipients with low antibody titers (≤1:4) after ABOi LKTx. One patient with blood type A1 who received a second ABOi LKTx from a type B donor did not produce B-specific antibodies. These findings suggest diminished donor-specific antibody production function in the setting of adult ABOi LKTx.

Treatment of large plasma volumes using specific immunoadsorption to desensitize ABO-incompatible kidney-transplant candidates

Background

ABO-incompatible (ABOi) kidney-transplantation has very good long-term results, i.e. similar to those observed for living-kidney ABO-compatible transplantation. This is because patients are desensitized at pretransplant using apheresis and rituximab therapy, with tacrolimus-based immunosuppression.

Objectives

To assess the efficacy of a single, pretransplant (Day –1), specific immunoadsorption session using Glycosorb® columns (anti-A or anti-B; Glycorex Sweden) to treat large volumes of plasma (up to 18 L).

Patients and Methods

Prospective single-center study evaluating 12 consecutive patients (6 males), aged 40 (23–59) years. Incompatibilities were A into 0 (8), B into 0 (3), and AB into 0 (1). Pretransplant desensitization relied on rituximab (D–30), tacrolimus, mycophenolic acid, and steroids (all started on D–13), and a single session of specific immunoadsorption on D–1. Immunoadsorption was coupled in tandem with a hemodialysis session.

Results

Overall, 15 L (11–18) of plasma were treated per patient, i.e., 0.2 (0.11–0.36 L/kg). Isoagglutinin titers were 1/16 (1/5–1/64) before the procedure, decreasing after 6 hours to 1/5 (1/1–1/16 P = 0.008), and to 1/2 (1/1–1/8; P = 0.05) at completion of the session. The next day, i.e., the day of transplantation, there was no rebound of isoagglutinins [1/4 (1/1–1/5); P = ns]. The procedure was well tolerated with no side-effects and no significant changes in hemoglobin level, platelet counts, fibrinogen, or albumin levels.

Conclusions

For ABOi kidney-transplantation, a single, longer, specific immunoadsorption session was very efficient at 1-day pre-transplantation with no rebound. These results should be confirmed when isoagglutinin titers are higher (≥120).

Desensitization for solid organ and hematopoietic stem cell transplantation

Desensitization protocols are being used worldwide to enable kidney transplantation across immunologic barriers, i.e. antibody to donor HLA or ABO antigens, which were once thought to be absolute contraindications to transplantation. Desensitization protocols are also being applied to permit transplantation of HLA mismatched hematopoietic stem cells to patients with antibody to donor HLA, to enhance the opportunity for transplantation of non-renal organs, and to treat antibody-mediated rejection. Although desensitization for organ transplantation carries an increased risk of antibody-mediated rejection, ultimately these transplants extend and enhance the quality of life for solid organ recipients, and desensitization that permits transplantation of hematopoietic stem cells is life saving for patients with limited donor options. Complex patient factors and variability in treatment protocols have made it difficult to identify, precisely, the mechanisms underlying the downregulation of donor-specific antibodies. The mechanisms underlying desensitization may differ among the various protocols in use, although there are likely to be some common features. However, it is likely that desensitization achieves a sort of immune detente by first reducing the immunologic barrier and then by creating an environment in which an autoregulatory process restricts the immune response to the allograft.

Late antibody-mediated rejection after ABO-incompatible kidney transplantation during Gram-negative sepsis

Background

The major challenge in ABO-incompatible transplantation is to minimize antibody-mediated rejection. Effective reduction of the anti-ABO blood group antibodies at the time of transplantation has made ABO-incompatible kidney transplantation a growing practice in our hospital and in centers worldwide. ABO antibodies result from contact with A- and B-like antigens in the intestines via nutrients and bacteria. We demonstrate a patient with fulminant antibody-mediated rejection late after ABO-incompatible kidney transplantation, whose anti-A antibody titers rose dramatically following Serratia marcescens sepsis.

Case presentation

A 58-year-old woman underwent an ABO-incompatible kidney transplantation for end-stage renal disease secondary to autosomal dominant polycystic kidney disease. It concerned a blood group A1 to O donation. Pre-desensitization titers were 64 for anti-blood group A IgM and 32 for anti-blood group A IgG titers. Desensitization treatment consisted of rituximab, tacrolimus, mycophenolate mofetil, corticosteroids, immunoadsorption and intravenous immunoglobulines. She was readmitted to our hospital 11 weeks after transplantation for S. marcescens urosepsis. Her anti-A IgM titer rose to >5000 and she developed a fulminant antibody-mediated rejection.

We hypothesized that the (overwhelming) presence in the blood of S. marcescens stimulated anti-A antibody formation, as S. marcescens might share epitopes with blood group A antigen. Unfortunately we could not demonstrate interaction between blood group A and S. marcescens in incubation experiments.

Conclusion

Two features of this post-transplant course are remarkably different from other reports of acute rejection in ABO-incompatible kidney transplantation: first, the late occurrence 12 weeks after kidney transplantation and second, the very high anti-A IgM titers (>5000), suggesting recent boosting of anti-A antibody formation by S. marcescens.

Significance of isoagglutinin titer in ABO-incompatible kidney transplantation

ABO-incompatible (ABO-i) kidney transplantation (KT) has emerged for overcoming the shortage of organ donors. Although this technique initially achieved only low graft survival due to isoagglutinin, recently developed desensitization protocols have improved survival to levels that are comparable to ABO-compatible KT. However, isoagglutinin is still regarded as a major obstacle to ABO-i KT. In this study, we evaluate the impact of isoagglutinin titer on clinical outcomes as well as factors that may influence isoagglutinin titers. In total, data from 95 patients who underwent ABO-i KT were analyzed. Preoperatively, rituximab administration and plasmapheresis were performed until the titer was reduced to ≤1:4. Retrospective analysis included blood group; timing and dosage of rituximab; isoagglutinin titer; number of plasmapheresis; and clinical outcomes including graft survival and serum creatinine. Graft survival was 95.8% (n = 91) and average serum creatinine at 1- and 1.5-year post-ABOi-KT was 1.3. Three patients died of sepsis. The identified predictors of titer-rebound after transplant were short interval (<7 days) between rituximab and first plasmapheresis (P = 0.004); high initial titer (≥256) (P = 0.023); low titer-reduction rate (P < 0.001); and blood group O (P < 0.001). One patient who experienced a rebound developed antibody-mediated rejection. With low-dose (200 mg) rituximab, the change in isoagglutinin titer-rebound was not significant and the infection rate was significantly decreased (P = 0.001). In conclusion, isoagglutinin titer-rebound within the first 2 weeks after KT may be a risk factor for rejection. The factors identified as affecting titer-rebound after KT were high initial isoagglutinin titer, low titer-reduction rate, short interval, and blood group O.

Anti-H can trigger apoptosis and down-regulate FUT1 expression in erythroid differentiated K562 cells without complement mediation

The reason why delayed RBC engraftment and pure red cell aplasia (PRCA) develop only in some but not all recipients of major ABO-incompatible hematopoietic stem cell transplantation (HSCT) remains elusive and the underlying mechanisms are not fully understood. Understanding how incompatible erythroid blood group antibodies (Abs) interact with ABH antigens (Ags) of grafts, and investigating how to induce artificially accommodation of grafts are of obvious importance in transplantation immunology. The effects of anti-H on proliferation, apoptosis, and α-(1,2)-fucosyltransferase gene (FUT1) expression in erythroid differentiated K562 cells were analyzed by the MTT assay, Annexin V/PI staining, and quantitative RT-PCR method. The growth of erythroid differentiated K562 cells was significantly suppressed when anti-H dilution was ≤ 1:8 (P<0.001, as compared with 1:16). Under the complement-free culture conditions, the apoptotic ratio of erythroid differentiated K562 cells was significantly increased when anti-H dilution was ≤ 1:16 (P<0.05, as compared with 1:32). The apoptosis was not only closely associated with anti-H dilution (F=138.991, P<0.001), but also correlated with treated time (F=583.249, P<0.001), which indicated typical dose- and time-dependent effects. Under the complement-free culture conditions, the FUT1 mRNA expression level was also suppressed when anti-H dilution was ≤ 1:16 (P<0.05, as compared with 1:32), which also manifested in typical dose-dependent (F=130.356, P<0.001) and time-dependent (F=1432.00, P<0.001) effects. The results confirm that anti-H can trigger apoptosis and down-regulate FUT1 expression in erythroid differentiated K562 cells without complement mediation. The findings suggest that anti-H could accommodate grafts through triggering apoptosis and down-regulating Fut1 expression to reduce ABH antigens.

ABO-incompatible kidney transplantation

Owing to the shortage of deceased donors in Japan, since 1989, we have performed ABO-incompatible kidney transplantation (ABO-IKTx) to expand the indication for living donor kidney transplantation. During the past two decades, about 2000 ABO-IKTxs were performed. Since 2001 the success rate for these kidney transplants has reached 96% for 1-year, 91% for 5-year and 83% for 9-year graft survival, similar to outcomes of ABO-compatible kidney transplantation (ABO-CKTx). This dramatic improvement in results means that ABO-IKTx has become accepted as a therapeutic alternative for end-stage renal failure. Today ABO-IKTx accounts for approximately 30% of all living donor kidney transplantations performed in Japan. We have been making a lot of efforts to elucidate the mechanism of acute antibody-mediated rejection in ABOI-KTx in order to overcome the ABO barrier and to improve the outcome. From careful and precise clinical observations, proteomic analysis of ABO histo-blood group antigens in graft endothelial cells and deep insight into immunology and biology, we have reached the hypothesis that the structural difference of ABO histo-blood group antigens and de novo corresponding antibody production would be the key and keyhole of the development of acute AMR in ABOI-KTx. Preoperative desensitization therapy would be the best solution for the suppression of acute AMR and graft loss, which is now widespread and improves the outcome.

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.

ABO-incompatible lung transplantation in an infant

Waitlist mortality continues to be a limiting factor for all solid-organ transplant programs. Strategies that could improve this situation should be considered. We report the first ABO-incompatible lung transplantation in an infant. The recipient infant was ABO blood group A1 and the donor group B. The recipient was diagnosed with surfactant protein B deficiency, which is a fatal condition and lung transplantation is the only definitive therapy. At 32 days of age, a bilateral lung transplantation from a donation after cardiac death (DCD) donor was performed. Intraoperative plasma exchange was the only preparatory procedure performed. No further interventions were required as the recipient isohemagglutinins were negative before transplant and have remained negative to date. At 6 months posttransplant, the recipient is at home, thriving, with normal development. This outcome suggests that ABO-incompatible lung transplantation is feasible in infants, providing another option to offer life-saving lung transplantation in this age range.

ABO Incompatible Kidney Transplantation-Current Status and Uncertainties

In the past, ABO blood group incompatibility was considered an absolute contraindication for kidney transplantation. Progress in defined desensitization practice and immunologic understanding has allowed increasingly successful ABO incompatible transplantation during recent years. This paper focused on the history, disserted outcomes, desensitization modalities and protocols, posttransplant immunologic surveillance, and antibody-mediated rejection in transplantation with an ABO incompatible kidney allograft. The mechanism underlying accommodation and antibody-mediated injury was also described.

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.

[An experience of ABO-incompatible kidney transplantation using plasmapheresis and anti-CD20 monoclonal antibody]

Due to an extreme shortage of cadaveric kidneys, many centers in Japan successfully performed ABO-incompatible kidney transplantations using plasmapheresis, splenectomy and immunosuppression. Recently, a protocol including anti-CD20 monoclonal antibody (rituximab) and antigen-selective immunoadsorption has been used for ABO-incompatible transplantation in Europe. In Korea, ABO-incompatible kidney transplantation has been rarely performed. We report an experience of successful ABO-incompatible kidney transplantation using plasmapheresis and rituximab. The patient was a 32-yr-old female suffering from chronic renal failure, and her blood type was O, Rh+. The donor was her husband, and his blood type was B, Rh+. A combination therapy including 5 times of plasmapheresis starting from 10 days before transplantation with 2-day interval, intravenous gammaglobulin, rituximab at 2 weeks before transplantation and potent immunosuppression successfully decreased the titers of anti-A and anti-B antibodies to 1:2 and 1:1, respectively. The kidney transplantation was successful without any sign of hyperacute or acute rejection.

Therapeutic plasma exchange for desensitization prior to transplantation in ABO-incompatible renal allografts

BACKGROUND

Although there have been desensitization protocols used for ABO-incompatible (ABOi) renal transplants, there are a lack of studied protocols. Our center developed a preconditioning protocol that involved mycophenolic acid, therapeutic plasma exchange (TPE), anti-CD20 monoclonal antibody (rituximab), and intravenous immunoglobulin (IVIG) that allowed for ABOi renal transplantation.

METHODS

Ten patients in our institution with end-stage renal disease who were unable to procure ABO-compatible donor kidneys underwent treatment with this protocol (which included a uniform 5 TPE sessions) prior to an ABOi renal transplant. A retrospective chart review was performed on these patients and clinical endpoints including ABO antibody titers, serum creatinine, clinical complications, and graft performance were analyzed.

RESULTS

The median ABO antibody titers at presentation, after completion of the protocol, and after transplant for the patients were 32 (range, 2-128), 8 (range, 1-64), and 4 (range, 2-32), respectively. The mean serum creatinine at study conclusion was 1.45 +/- 1.04 mg/dl at an average of 262.20 days from transplant. There were four incidents of antibody-mediated rejection (AMR) and two incidents of delayed graft function (DGF). There was one incident of graft failure and no patient deaths.

CONCLUSIONS

The desensitization protocol used by our institution allowed for successful ABOi renal transplantation. Although there were incidents of AMR and DGF, the majority of the transplants resulted in viable grafts. A larger patient study group may be needed to fully evaluate the efficacy and safety of this protocol.

Identification and characterization of major proteins carrying ABO blood group antigens in the human kidney

BACKGROUND

It is generally admitted that ABO(H) blood group antigens are linked to lipids and proteins. Although glycolipids carrying ABO antigens have been well characterized in human kidneys, glycoproteins carrying ABO antigens are largely unknown, and their molecular properties remain to be elucidated.

METHODS

All the blood group A antigen-linked proteins in human kidney could be solubilized and captured on immobilized Helix pomatia lectin that recognizes A antigens. These proteins were separated on SDS-PAGE gels. The gel pieces containing protein bands immunoreactive with anti-A antibody were excised, in-gel digested with trypsin, and analyzed by nanoLC tandem mass spectrometer. Protein candidates that carry ABO antigens were confirmed by immunoprecipitation and double-labeled immunofluorescense microscopy.

RESULTS

All the glycoproteins carrying ABO antigens were found to be Asn-linked glycoproteins, and presented as multiple bands on SDS-PAGE with molecular masses ranging from 60 to 270 kDa. The protein bands were subjected for mass spectrometric analysis, which identified 121 distinct proteins with high confidence. Of the identified proteins, 55 N-glycosylated, membrane proteins were selected as glycoprotein candidates that carry ABO antigens. Among them, most abundantly expressed proteins as estimated by the number of peptide matches in the MS spectrometric analysis, such as platelet endothelial cell adhesion molecule 1, plasmalemmal vesicle-associated protein, and von Willebrand factor, were further characterized.

CONCLUSIONS

Several glycoproteins were identified that represented major glycoproteins carrying ABO antigens in the human kidney, which exhibited distinct features in localization to most of vascular endothelial cells.

Multicenter experience of ABO-incompatible pediatric cardiac transplantation

Although ABO blood group incompatible cardiac transplantation in neonates and infants reduces waiting list mortality without compromising outcome, the technique has not been adopted by all centers, and to date Toronto remains the only center to have published results from a large case series. We present a review of ABO-incompatible heart transplantation in the United Kingdom (UK) where current recipient selection criteria differ somewhat from those used in the United States (US) and Canada. Between February 2000 and November 2006, 21 ABO-incompatible cardiac transplants were performed in children aged 2-40 months (median 10.0). Immunosuppression followed standard regimens. Pretransplant donor-specific isohemagglutinins of >1:4, (the UNOS cutoff), were present in five patients and reduced by plasma exchange. After transplantation, 19/21 recipients demonstrated persisting deficiency of donor-specific isohemagglutinins. Significant donor-specific isohemagglutinins levels were detected repeatedly in 2/21 recipients who have shown no clinical or biopsy evidence of rejection. All recipients survive without retransplantation and there have been no episodes of humoral rejection. We conclude it is possible for other centers to replicate the excellent results achieved in Toronto and that ABO-incompatible transplantation may be performed successfully in some patients beyond infancy with established isohemagglutinin production providing preoperative antibody removing strategies are used.

Monoclonal anti-A antibody removal by synthetic A antigen immobilized on specific antibody filters

Removal of blood group anti-A and anti-B antibodies can prevent hyperacute organ rejection in ABO-incompatible transplantation. We are developing an extracorporeal-specific antibody filter (SAF) as an immunoadsorption device for direct removal of ABO blood group antibodies from whole blood, without the need for plasma separation and plasma exchange. A hollow fiber-based small scale SAF (mini-SAF) device was fabricated and synthetic A antigen, Atrisaccharide (Atri) conjugated to activated polyacrylic acid, was immobilized on the fiber lumen surface. Monoclonal antibody anti-A IgM were specifically removed up to 70% of initial antibodies using mini-SAF device. The monoclonal anti-A capture experiments on mini-SAF indicated that antibody removal relative to the initial concentration is independent of inlet concentration in the beginning; however, as the surface starts saturating with bound antibodies, removal becomes dependent on inlet concentration. No significant effect of flow rate on removal rate was observed. The radial diffusion and axial convection-based mathematical model developed for unsteady state antibody removal was in good agreement with the experimental data and showed that the antibody removal rate can be maximized by increasing the antibody-binding capacity of the SAF.

Recent findings in ABO-incompatible kidney transplantation: classification and therapeutic strategy for acute antibody-mediated rejection due to ABO-blood-group-related antigens during the critical period preceding the establishment of accommodation

In Japan, ABO-incompatible kidney transplantation has been performed in more than 1000 patients since 1989, and recently accounts for about 18% of all living donor kidney transplants. As for outcomes, since 2001 the 1-year and 3-year graft survival rates have increased to 96% and 94%, respectively, which are similar to those in ABO-compatible transplantation. These improved outcomes are attributed to a clearer understanding of the mechanisms underlying accommodation and acute antibody-mediated rejection, permitting the development of new therapeutic strategies. This review classifies and discusses the clinical significance of acute antibody-mediated rejection due to ABO-blood-group-related antigens during the critical period preceding the establishment of accommodation.

Endothelial cells in organ transplantation: Friends or foes?

Vascular endothelial cells are the first interface between donor and recipient in organ transplantation. Endothelial cells and smooth muscle cells are key actors of acute and chronic rejection processes in organ allografting, but they also have the capacity to protect themselves from allograft-induced injury. Recent advances in our understanding of the precise mechanisms leading to endothelial dysfunction or, on the contrary, to endothelial protection, suggest that therapeutic interventions targeting endothelial cells could improve allograft survival and have even raised the question of whether such manipulations can be considered with a view to inducing immunological tolerance.

ABO-incompatible kidney transplantation using antigen-specific immunoadsorption and rituximab: a single center experience

BACKGROUND

For years ABO-incompatible kidney transplantations were preferentially performed in Japanese centers. In order to overcome the increased risk of humoral rejections, patients were treated with multiple sessions of plasmapheresis, intensified immunosuppressive therapy and splenectomy before transplantation. Despite good long-term results regarding patient and organ survival rates, increased morbidity during the early post-transplant period prevented a broad application of this method. Recently, a new protocol including the anti-CD20-antibody (Ab) rituximab and blood group-specific immunoadsorption instead of splenectomy and plasmapheresis was published with excellent short-term results.

METHODS

From April 2004 to September 2005, 11 patients were prepared for ABO-incompatible transplantation. All patients received 375 mg/m2 rituximab intravenous 3 to 4 weeks before transplantation. Immunosuppressive therapy consisted of tacrolimus, mycophenolate mofetil and prednisone and was started at least 7 days before transplantation. Intravenous immunoglobulins (0.5 g/kg) were administered the day before transplantation. Immunoglobulin G (IgG)-anti-A or -B Ab titers before starting immunoadsorption treatment ranged between 1 : 4 and 1 : 1024. Immunoadsorption treatment was started in parallel with immunosuppressive medication and was continued until the anti-A or anti -B Ab titers (IgG and IgM) were lowered to the aimed pre-transplant threshold of <1 : 8. During the early postoperative period, additional immunoadsorption treatments were performed, if the titers increased again above 1 : 8 (days 0 to 7) or 1 : 16 (days 8 to 14), respectively.

RESULTS

Transplantation could be conducted in eight of 11 patients (two females, six males, mean recipient age 52+/-11 yr). The mean follow-up was 7.0 months (range 4 to 17). The blood group constellation was A1 to 0 in four cases, A2 to 0 in two cases, B to A in one case, and A1 to B in another case, respectively. On average, each patient received seven immunoadsorption treatments. All transplants showed primary function and no humoral rejections occurred. Three of our 11 patients showed rapid increases of isoagglutinin titers after each immunoadsorption treatment and thus could not be transplanted. One patient died 4 months after transplantation with a functioning graft due to sepsis secondary to pseudomembranous enterocolitis. The mean creatinine value of the remaining seven patients now is 1.6 mg/dl.

SUMMARY

The use of antigen-specific immunoadsorption and an immunosuppressive regimen consisting of a conventional triple immunosuppressive therapy has shown excellent short-term results. The immunoadsorption treatment using antigen-specific columns is highly effective and even patients with high isoagglutinin titers can be transplanted. This protocol is an option for end-stage renal disease patients who have no blood group-compatible donor.

Pinpoint targeted immunosuppression: anti-CD20/MMF desensitization with anti-CD25 in successful ABO-incompatible kidney transplantation without splenectomy

BACKGROUND

In Japan, ABO-incompatible (ABO-I) kidney transplantation began in 1989; these transplantations have flourished because of the lack of cadaveric donors, and more than 600 cases were performed up to 2004. Splenectomy has been considered to be necessary for successful ABO-I kidney transplantation, and the majority of pre-conditioning protocols include splenectomy in Japan. However, we have lost some grafts due to antibody-mediated rejection (AMR) accompanying explosive elevation of anti-A/B antibody (Ab) titer even though the patients had a low pre-operative Ab titer.

PATIENTS AND METHODS

We utilized two doses of anti-CD20, rituximab, simply combined with mycophenolate mofetil (MMF)/low-dose steroid desensitization started 1 month before surgery in ABO-I kidney transplantation. Two sessions of pre-operative Ab removal by double filtration plasmapheresis or plasma exchange were carried out. We performed six ABO-I kidney transplantations without splenectomy. Anti-A/B Ab titers were more than 16 to 32 times before treatment. We did not plan any post-operative repeated Ab removal or intravenous immunoglobulin G (IVIG).

RESULTS

Pre-operative anti-A/B Ab titers were successfully reduced to less than eight times in all cases. Except for one case in which we had to remove the graft due to aspiration pneumonia and methicillin-resistant staphylococcus epidermidis (MRSE) sepsis, the other five cases did not experience antibody-mediated rejection (AMR). An additional session of post-operative Ab removal and/or IVIG was not necessary. In all patients, B cells (CD19+, CD20+, CD21+) and activated T cells (CD25+) were selectively suppressed, although CD3+, CD4+ and CD8+ cell populations remained stable, thus we call our protocol "pinpoint targeted immunosuppression." Plasma immunoglobulin level was also successfully suppressed, especially after 6 weeks of surgery.

CONCLUSION

Anti-CD20/MMF desensitization is safe and allows successful ABO-I kidney transplantation without splenectomy.

Present status of ABO-incompatible kidney transplantation in Japan

BACKGROUND

We have been making continuous efforts in ABO-incompatible kidney transplantation since 1989 to expand the opportunities for kidney transplantation from living donors in Japan.

PATIENTS AND METHOD

From the Japanese registry, we reviewed the long-term patient and graft survival of ABO-incompatible kidney transplantation. This survey focused on 564 patients who received ABO-incompatible kidney grafts from January 1989 to December 2003 in whom monitoring follow-up could be achieved in 60 institutions all over Japan. The mean age of 367 (65%) male and 197 (35%) female patients at surgery was 34.5 yr. Pre-operative anti-A/B antibody (Ab) removal and splenectomy (n = 553, 98%) were routinely performed combined with triple or quadruple immunosuppression using calcinurine inhibitor (CNI), anti-metabolites and steroids with or without deoxyspurgualin (DSG) or anti-lymphocyte Abs.

RESULTS

The overall patient survival rate at 1, 3, 5 and 10 yr after transplantation was 94, 91, 88 and 81%, with overall graft survival rates of 86, 82, 74 and 53%, respectively. The graft survival rate was significantly higher in patients aged 29 and younger compared with those aged 30 and older. Children aged 15 or younger in particular have shown excellent graft survival rates at 1, 3, 5 and 10 yr of 90, 90, 86 and 76%, respectively. Patients with anticoagulation therapy (n = 285) showed a significantly higher graft survival rate than those without anticoagulation (n = 213), with 10-yr graft survival rates of 59 vs. 48%. There were no significant differences between A and B incompatibility with respect to clinical outcomes. There were also no significant difference in numbers of human leukocyte antigen mismatches, induction and maintenance CNI (cyclosporin A (CYA) vs. tacrolimus) and donor/recipient relationships with respect to the outcomes. We divided the patients into five groups according to the transplanted year periods. The outcome of the most recent 124 cases since 2001 had dramatically improved, with 2-yr graft survival of 94%, and there is a significant difference between the groups in 2001 onwards and the other four groups.

CONCLUSION

This study confirms that the long-term outcome of ABO-incompatible living kidney transplantation is excellent and is similar to that of ABO-compatible cases. Recent data show that short-term graft survival has also improved. ABO-incompatible kidney transplantation is a radical, but safe and effective, treatment choice for end-stage renal disease.

A new concept of accommodation in ABO-incompatible kidney transplantation

This work focuses on the mechanism of acute antibody-mediated rejection leading to graft loss and the mechanisms of accommodation permitting graft survival in ABO-incompatible kidney transplantation. As previously noted, accommodation occurs only with (i) post-transplant suppression of glycosyltransferase, a product of ABO histo-blood group genes in the graft and (ii) prevention of antigen-antibody reactions and delayed hyperacute rejection due to reduced antigenicity of enzyme-regulated histo-blood group antigens. This article discusses the mechanism of ABO histo-blood group glycosyltransferase suppression. Accommodation is always established in successful ABO-incompatible organ grafts and ABO-minor mismatch bone marrow transplantation. In the former, accommodation develops even though ABO histo-blood types of the recipient and the donor are incompatible. In the latter, infusion of donor-derived bone marrow causes the recipient's blood to be eventually replaced by blood of the donor's type. However, the recipient's organs retain their original tissue type. In successful bone marrow engraftment, accommodation is established regardless of ABO-incompatibility. In organ transplantation the recipient's ABO histo-blood type regulates the graft's ABO histo-blood type, while in bone marrow transplantation the new ABO histo-blood type from the donor suppresses and regulates the ABO histo-blood type in recipient organs. In other words, bone marrow-derived histo-blood type regulates the histo-blood type of the organs.

Isotype-specific detection of ABO blood group antibodies using a novel flow cytometric method

Several methods to detect anti-A/B antibodies based on haemagglutination and haemolysis have been described. These methods measure predominantly anti-A/B immunoglobulin (Ig)M, whereas anti-A/B IgG and IgG subclasses are less well examined. We established a flow cytometry method (ABO-fluorescence-activated cell sorting; ABO-FACS) to quantify binding of anti-A/B IgM, IgG and IgG subclasses to human A or B red blood cells. Anti-A/B IgM were present in the majority of 120 blood donors, as expected from blood group typing. The sensitivity and specificity of anti-A/B IgM to predict the blood group was 93% and 96% respectively. Anti-A/B IgG was found in 34/38 blood group O samples (89%). Anti-B IgG in blood group A or anti-A IgG in blood group B was present in 4/28 (14%) and 1/28 (4%) samples, respectively, and absent in 26 AB sera. IgG2 was the predominant IgG subclass. The correlation of anti-A/B IgM and IgG in the ABO-FACS with haemagglutination titres was 0.870 and 0.783, respectively (n = 240; P < 0.001) whereas the comparison of ABO-FACS with ABO-enzyme-linked immunosorbent assay was less significant. In conclusion, ABO-FACS is a valid method to quantify anti-A/B IgM, IgG and IgG subclasses. It opens the possibility of isotype-specific monitoring of anti-A/B antibodies levels after ABO-incompatible solid organ and stem cell transplantation.

Successful results after 5 years of tacrolimus therapy in ABO-incompatible kidney transplantation in Japan

In Japan, living donor kidney transplantation accounts for about 80% of all kidney transplants. This is in contrast to the United States and Europe, where transplantation of organs from cadaveric or brain-dead donors is more common. This study analyzed the results of 5 years of experience with tacrolimus in Japan, focusing on the efficacy of the drug in improving patient and graft survival in patients who underwent transplantation with ABO-incompatible kidney grafts. Of the 1542 evaluable patients, 1281 patients received grafts from living donors. Of these, 177 patients received kidneys from ABO-incompatible donors and 981 patients received kidneys from ABO-compatible donors. Graft survival rates in ABO-incompatible recipients ranged from 90.7% at 1 year to 80.5% at 5 years. Subsequent graft survival rates in ABO-compatible recipients were 98.1% and 92.9%, respectively (P < .001 between groups). Patient survival rates at 5 years were 93.2% in ABO-incompatible recipients and 98.1% in ABO-compatible recipients. The rejection rate for kidneys from ABO-compatible donors was 27.8%, while for ABO-incompatible donors the rejection rate was 45.2%. The excellent outcome from this study demonstrates that even suboptimal ABO-incompatible donors can be used successfully as a source of kidneys when using tacrolimus as the immunosuppressive regimen. This may go some way to addressing the shortage of kidney donors in Japan.

Is the ABO incompatibility a risk factor in bone marrow transplantation?

ABO histo-bloodgroups are strong transplantation antigens. In bone marrow transplantation, foreign ABO red cell antigens are not ignored by the immune system of the host, neither by the immunocompetent cells of the graft. Although ABO incompatibility is not considered a contraindication in bone marrow transplantation (BMT), its clinical consequences are still a matter of investigation. An overview of reports published by different groups is given and discussed. They present conflicting data regarding the role of the ABO match between patient and donor in the haematopoietic stem cell (HSC) transplantation. We report on the clinical outcome of bone marrow transplantation in 223 patients who received grafts from MHC identical siblings. Included are 139 ABO identical, 32 ABO minor mismatched, 34 major mismatched and 13 bi-directionally mismatched pairs. The statistical evaluation of standard parameters used to monitor the post-transplant period gave a proof that in neither group of patients with an ABO incompatible donor the recovery and success rate of transplantation, including the relapse incidence, risk of graft vs. host disease (GVHD) or overall survival, were significantly inferior. However, in all three cohorts of ABO mismatched patients, a delayed recovery of neutrophils was recorded as compared to the group receiving an ABO compatible graft. These finding leads us to the conclusion that the ABO compatibility is not a disadvantage in BMT, whereas the delayed recovery of neutrophils in patients having received an ABO mismatched graft is probably reflecting a transient humoral process leading to immune tolerance and graft accommodation.

Improved Outcomes after ABO-Incompatible Living-Donor Kidney Transplantation after 4 Weeks of Treatment with Mycophenolate Mofetil

Hyperacute humoral rejection of ABO-incompatible kidney transplants limits the application of this procedure. We evaluated the effect of 4-week treatment with mycophenolate mofetil (MMF), a compound that inhibits antibody production by B cells, before ABO-incompatible living-donor kidney transplantation with tacrolimus as the primary immunosuppressant. In contrast with cases without MMF pretreatment, we did not observe any graft loss caused by hyperacute humoral rejection in the 18 patients who received MMF. Overall, the incidence of adverse events was comparable in the MMF-treated and -untreated groups. The administration of MMF 4 weeks before kidney transplant effectively inhibits B-cell function, suggesting a potential role for MMF in the prevention of humoral rejection.