Successful management of an ABO-mismatched lung allograft using antigen-specific immunoadsorption, complement inhibition, and immunomodulatory therapy

Intentional Lung Transplantation Due to ABO Incompatibility: A Case Report

We present a case of a 16-year-old adolescent female with blood group O+ who was diagnosed with cystic fibrosis (CF). The patient had to be hospitalized due to septic shock and respiratory failure, and extracorporeal membrane oxygenation and mechanical ventilation were applied. Faced with high urgency, she was promptly enlisted for a lung transplant, ultimately receiving a blood group A1 deceased donor lung through rescue allocation. Bilateral incompatible lung transplantation, with parental consent, was successfully performed. The postoperative course was favorable, marked by the administration of rabbit anti-thymocyte globulin, plasmapheresis, and immunosuppression (mycophenolate, steroids, and tacrolimus) as per the prescribed protocol. Notably, the patient experienced a smooth recovery without infectious complications or humoral rejection. This case highlights the viability of lung transplantation in cases of ABO incompatibility, particularly for patients in urgent need on the transplant waiting list.

The first successful case of ABO-incompatible living-donor lobar lung transplantation following desensitization therapy

ABO-incompatible (ABO-I) living-donor lobar lung transplantation (LDLLT) was successfully performed in a 14-year-old girl who suffered from bronchiolitis obliterans due to graft-versus-host disease following hematopoietic stem cell transplantation. In the ABO-I LDLLT procedure, the blood type O patient received a right lower lobe donated from her blood type B father and a left lower lobe donated from her blood type O mother. Desensitization therapy, using rituximab, immunosuppressants, and plasmapheresis, was implemented for 3 weeks prior to transplantation to reduce the production of anti-B antibodies in the recipient and prevent acute antibody-mediated rejection after ABO-I LDLLT.

Expanding Donor Options for Lung Transplant: Extended Criteria, Donation After Circulatory Death, ABO Incompatibility, and Evolution of Ex Vivo Lung Perfusion

Only using brain-dead donors with standard criteria, the existing donor shortage has never improved in lung transplantation. Currently, clinical efforts have sought the means to use cohorts of untapped donors, such as extended criteria donors, donation after circulatory death, and donors that are ABO blood group incompatible, and establish the evidence for their potential contribution to the lung transplant needs. Also, technical maturation for using those lungs may eliminate immediate concerns about the early posttransplant course, such as primary graft dysfunction or hyperacute rejection. In addition, recent clinical and preclinical advances in ex vivo lung perfusion techniques have allowed the safer use of lungs from high-risk donors and graft modification to match grafts to recipients and may improve posttransplant outcomes. This review summarizes recent trends and accomplishments and future applications for expanding the donor pool in lung transplantation.

Hypotheses of the origin of natural antibodies: a glycobiologist's opinion

It is generally accepted that the generation of antibodies proceeds due to immunization of an organism by alien antigens, and the level and affinity of antibodies are directly correlated to the presence of immunogen. At the same time, vast experimental material has been obtained providing evidence of antibodies whose level remains unchanged and affinity is constant during a lifetime. In contrast to the first, adaptive immunoglobulins, the latter are named natural antibodies (nAbs). The nAbs are produced by B1 cells, whereas adaptive Abs are produced by B2. This review summarizes general data on nAbs and presents in more detail data on antigens of carbohydrate origin. Hypotheses on the origin of nAbs and their activation mechanisms are discussed. We present our thoughts on this matter supported by our experimental data on nAbs to glycans.

Postoperative rebound of antiblood type antibodies and antibody-mediated rejection after ABO-incompatible living-related kidney transplantation

The purpose of this study is to examine whether postoperative antiblood type antibody rebound is attributed to kidney allograft rejection in ABO blood type-incompatible (ABO-I) living-related kidney transplantation (KTx). A total of 191 ABO-I recipients who received ABO-I living-related KTx between 2001 and 2013 were divided into two groups: Group 1 consisted of low rebound [(≦1:32), N = 170] and Group 2 consisted of high rebound [(≧1:64), N = 21], according to the levels of the rebounded antiblood type antibodies within 1 year after transplantation. No prophylactic treatment for rejection was administered for elevated antiblood type antibodies, regardless of the levels of the rebounded antibodies. Within 1 year after transplantation, T-cell-mediated rejection was observed in 13 of 170 recipients (13/170, 8%) in Group 1 and in 2 of 21 recipients (2/21, 10%) in Group 2 (Groups 1 vs. 2, P = 0.432). Antibody-mediated rejection was observed in 15 of 170 recipients (15/170, 9%) and 2 of 21 recipients (2/21, 10%) in Groups 1 and 2, respectively (P = 0.898). In this study, we found no correlation between the postoperative antiblood type antibody rebound and the incidence of acute rejection. We concluded that no treatment is necessary for rebounded antiblood type antibodies.

Adult Living Donor Liver Transplantation Across ABO-Incompatibility

The objective of this study was to evaluate the results of adult ABO-incompatible living donor liver transplantation (LDLT).ABO-incompatible LDLT is an aggressive treatment that crosses the blood-typing barrier for saving lives from liver diseases. Although graft and patient survival have been improved recently by various treatments, the results of adult ABO-incompatible LDLT require further evaluation.Two regimens were designed based on isoagglutinin IgG and IgM titers and the time course of immunological reactions at this institute. When isoagglutinin IgG and IgM titers were ≤64, liver transplantation was directly performed and rituximab (375 mg/m) was administrated on postoperative day 1 (regimen I). When isoagglutinin titers were >64, rituximab (375 mg/m) was administered preoperatively with or without plasmapheresis and boosted on postoperative day 1 (regimen II). Immunosuppression was achieved by administration of mycophenolate mofetil, tacrolimus, and steroids.Forty-six adult ABO-incompatible and 340 ABO-compatible LDLTs were performed from 2006 to 2013. The Model for End-Stage Liver Disease scores for ABO-incompatible recipients ranged from 7 to 40, with a median of 14. The graft-to-recipient weight ratio ranged from 0.61% to 1.61% with a median of 0.91%. The 1-, 3-, and 5-year survival rates were 81.7%, 75.7%, and 71.0%, respectively, for ABO-incompatible LDLT recipients, compared to 81.0%, 75.2%, and 71.5% for ABO-C recipients (P = 0.912). The biliary complication rate was higher in ABO-incompatible LDLT recipients than in the ABO-compatible recipients (50.0% vs 29.7%, P = 0.009).In the rituximab era, the blood type barrier can be crossed to achieve adult ABO-incompatible LDLT with survival rates comparable to those of ABO-compatible LDLT, but with more biliary complications.

Molecular deciphering of the ABO system as a basis for novel diagnostics and therapeutics in ABO incompatible transplantation

In recent years ABO incompatible kidney transplantation (KTx) has become a more or less clinical routine procedure with graft and patient survival similar to those of ABO compatible transplants. Antigen-specific immunoadsorption (IA) for anti-A and anti-B antibody removal constitutes in many centers an important part of the treatment protocol. ABO antibody titration by hemagglutination is guiding the treatment; both if the recipient can be transplanted as well as in cases of suspected rejections if antibody removal should be performed. Despite the overall success of ABO incompatible KTx, there is still room for improvements and an extension of the technology to include other solid organs. Based on an increased understanding of the structural complexity and tissue distribution of ABH antigens and the fine epitope specificity of the ABO antibody repertoire, improved IA matrices and ABO antibody diagnostics should be developed. Furthermore, understanding the molecular mechanisms behind accommodation of ABO incompatible renal allografts could make it possible to induce long-term allograft acceptance also in human leukocyte antigen (HLA) sensitized recipients and, perhaps, also make clinical xenotransplantation possible.

Lessons and insights from ABO-incompatible lung transplantation

With ABO blood group incompatibility (ABOi) between donor and recipient becoming a part of mainstream living-donor renal transplantation, the applicability of ABOi to other areas of transplantation is being reconsidered. Here we present a case of inadvertent ABOi lung retransplantation managed successfully with initial plasmapheresis, antithymocyte globulin and intravenous immunoglobulin; and subsequently with oral cyclophosphamide and sirolimus in addition to tacrolimus and prednisolone. Interestingly, in the setting of solid levels of tacrolimus and sirolimus, the patient developed a fatal thrombotic microangiopathy of uncertain origin subsequent to the cessation of cyclophosphamide at 9 years posttransplant. It is apparent that ABOi lung transplantation can result in surprisingly successful long-term outcomes. Low pretransplant antibody titers likely aid this and, in pediatric neonatal or infant cases, this may not be uncommon. We must proceed cautiously as there are significant risks. Understanding the monitoring, prevention and treatment of lung transplant antibody-mediated rejection, while avoiding the long-term complications of overimmunosuppression, will be the keys to the success of future cases.

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.

Current progress in ABO-incompatible liver transplantation

BACKGROUND

ABO-incompatible (ABOi) living donor liver transplantation (LDLT) in adult patients has been controversial because of the high risk of antibody-mediated rejection (AMR) mediated by preformed anti-ABO antibodies. However, outcomes have recently improved owing to various treatment advances.

MATERIALS AND METHODS

This review article describes the history and current progress in ABOi liver transplantation, mainly from the viewpoint of the Japanese experience.

RESULTS

The typical clinical manifestations of AMR are hepatic necrosis and intrahepatic biliary complication. The outcomes of early ABOi LDLT were poor, especially in older children and adult cases. Since we first introduced portal vein infusion therapy into adult ABOi LDLT in 1998, local graft infusion therapy has emerged in Japan as a crucial breakthrough to overcome the ABO blood group barrier. From 2003, rituximab prophylaxis has been widely used with local graft infusion, and has resulted in markedly improved patient survival. The novel approach of intravenous immunoglobulin induction may become another option to suppress AMR. Continued patient enrollment and controlled trials will allow further validation of these treatments.

CONCLUSIONS

The outcome of ABOi LDLT is now similar to that of blood-type-matched transplantation in Japan. However, infection is the major cause of morbidity and mortality after ABOi LDLT. Thus, evaluation of the patients' immune status and adjustment of immunosuppression will be the way forward in the future.

Isoagglutinin adsorption in ABO-incompatible transplantation

As the demand for kidney transplantation is constantly growing methods to expand the donor pool have become increasingly important. ABO-incompatibility has hitherto been regarded as an absolute contraindication to living donor donation. However, as ABO-incompatibility has accounted for the majority of living donor exclusions, efforts have been made to overcome this immunologic barrier. Successful desensitization protocols thus far, have combined plasmapheresis for antibody removal with splenectomy to reduce the antibody producing B-cell pool, in addition to quadruple immunosuppression. Although good graft function has been achieved, the high risks involved have been deterrent. We have developed a protocol for ABO-incompatible kidney transplantation based on antigen-specific immunoadsorption and rituximab, in combination with standard maintenance immunosuppression (tacrolimus, mycophenolate mofetil and corticosteroids). We hypothesized that the anti-A/B antibodies could be effectively eliminated and good graft function achieved, without the complications of coagulopathy and transfusion reactions associated with plasmapheresis. Furthermore, we hypothesized that the substitution of splenectomy with a single dose of the anti-CD20 antibody rituximab would further reduce surgical risk as well as the risk of infectious complications. In 2001 the program for ABO-incompatible kidney transplantation was started at our center. To date 50 ABO-incompatible kidney transplantations have been performed according to the protocol based on antigen-specific immunoadsorption and rituximab. Safety and efficacy of the protocol has been evaluated in several studies, all showing that the antigen-specific immunoadsorption is well tolerated and without any serious side effects. Patient and graft survival as well as kidney function have been comparable to that of ABO-compatible living donor kidney transplantation and the incidence of antibody-mediated rejection 0%. We conclude that AB0-incompatible kidney transplantation using a protocol based on antigen-specific immunoadsorption and rituximab, in combination with triple immunosuppressive therapy is safe and effective. ABO-incompatibility following this protocol does not have a negative impact on graft function. ABO-incompatible kidney transplantation is equivalent to standard ABO-compatible living donor kidney transplantation.

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.

Anti-HLA I antibodies induce VEGF production by endothelial cells, which increases proliferation and paracellular permeability

Anti-human leukocyte antigen class I (HLA I) antibodies were shown to activate several protein kinases in endothelial cells (ECs), which induces proliferation and cell survival. An important phenomenon in antibody-mediated rejection is the occurrence of interstitial edema. We investigated the effect of anti-HLA I antibodies on endothelial proliferation and permeability, as one possible underlying mechanism of edema formation. HLA I antibodies increased the permeability of cultured ECs isolated from umbilical veins. Anti-HLA I antibodies induced the production of vascular endothelial growth factor (VEGF) by ECs, which activated VEGF receptor 2 (VEGFR2) in an autocrine manner. Activated VEGFR2 led to a c-Src-dependent phosphorylation of vascular endothelial (VE)-cadherin and its degradation. Aberrant VE-cadherin expression resulted in impaired adherens junctions, which might lead to increased endothelial permeability. This effect was only observed after cross-linking of HLA I molecules by intact antibodies. Furthermore, our results suggest that increased endothelial proliferation following anti-HLA I treatment occurs via autocrine VEGFR2 activation. Our data indicate the ability of anti-HLA I to induce VEGF production in ECs. Transactivation of VEGFR2 leads to increased EC proliferation and paracellular permeability. The autocrine effect of VEGF on endothelial permeability might be an explanation for the formation of interstitial edema after transplantation.

Intentional ABO-incompatible lung transplantation

We report on a case of intentional blood group incompatible lung transplantation. A blood group O cystic fibrosis patient was mechanically ventilated and put on interventional lung assist for severe respiratory decompensation. Since timely allocation of a blood group O donor lung was impossible, an AB deceased donor lung rescue allocation was accepted and the transplant performed using a pre-, peri- and postoperative antibody depletion protocol including plasmapheresis, ivIg administration, rituximab and immunoadsorption. Nine months after the transplant the patient is at home and well.

New treatments for acute humoral rejection of kidney allografts

Acute antibody-mediated rejection (acute humoral rejection; AHR) of organ allografts usually presents as severe dysfunction with a high risk of allograft loss. Peritubular capillary complement C4d deposition with renal dysfunction, associated with circulating donor-specific anti-human leukocyte antigen alloantibodies, is diagnostic of AHR in kidney allografts. Removal of alloantibodies with suppression of antibody production and rejection reversal is now possible. Therapeutic strategies that include combinations of plasmapheresis (or immunoadsorption), tacrolimus, mycophenolate mofetil and/or intravenous immunoglobulins, as well as rituximab or splenectomy, have been recently used to successfully treat AHR. However, the optimal protocol to treat AHR still remains to be defined. Anti-CD20+ monoclonal antibody therapy (rituximab) aiming at depleting B cells and suppressing antibody production has been used as rescue therapy in some episodes of steroid- and antilymphocyte-resistant humoral rejection. Plasmapheresis and/or intravenous polyclonal immunoglobulin, as well as rituximab, have also been used to successfully desensitize selected high-immunological risk patients in anticipation of a previously cross-match positive (or ABO incompatible) kidney transplantation. In the near future, the possible role of new specific anti-B-cell approaches or, possibly, of new anti-T-cell activation approaches using selective agents such as belatacept should be assessed to further refine the present treatment of humoral rejection.

Successful Management of Antibody-Mediated Cardiac Allograft Rejection With Combined Immunoadsorption and Anti-CD20 Monoclonal Antibody Treatment: Case Report and Literature Review

Chronic rejection is still the major limitation of long-term outcome of heart transplant recipients. Several recent studies demonstrated that a not negligible proportion of chronic allograft rejection episodes are not only mediated by T-cell response but also triggered by pre-transplant and de novo post-transplant donor-specific alloantibodies. This points at a fundamental role of humoral immune response mechanisms that contribute to early and late graft failure. This type of rejection is an unsolved problem solid organ transplantation because current immunosuppressive regimens are generally intended to interfere in T-cell signalling pathways. Various options for the removal of circulating alloantibodies and the prevention of alloantibody formation by B-cell depletion have been described. Nevertheless, effective standardized schemes for the treatment of antibody-mediated graft rejection have to be defined. We present a heart transplant recipient with sustained antibody-mediated graft rejection who was successfully managed with a combination treatment consisting of 3 cycles of immunoadsorption and a single-dose administration of the anti-CD20 monoclonal antibody rituximab.

Experiences and problems pre-operative anti-CD20 monoclonal antibody infusion therapy with splenectomy and plasma exchange for ABO-incompatible living-donor liver transplantation

BACKGROUND

ABO-incompatible living-donor liver transplantation (LDLT) requires a reduction of the anti-ABO antibody titer to <16 before transplantation, which is usually achieved by pre-operative plasma exchange (PE) or double-filtration plasmapheresis. ABO-incompatible transplantations have been performed after a splenectomy with heavy drug immunosupression plus B-cell-specific drugs. Here, we evaluated a pre-transplantation infusion protocol with an anti-CD20 monoclonal antibody (rituximab) for ABO-incompatible LDLT.

METHODS

Between March 2002 and December 2005, 73 adult patients underwent LDLT without retransplantation in our institution. Among these cases, 57 were ABO-identical, 11 were ABO-compatible and five were ABO-incompatible. The rituximab infusion protocol consisted of a weekly infusion of rituximab (375 mg/m(2)) for three wk, which was administered to three of the five ABO-incompatible LDLT patients. All three patients underwent a pre-operative PE, as well as a splenectomy during the operation. A triple immunosuppression protocol of tacrolimus, low-dose steroids and mycophenolate mofetil (1500 mg/d) was administered post-operatively. In addition, the patients received a continuous intra-arterial infusion of prostaglandin E(1) and methylprednisolone, and a continuous intra-portal infusion of a protease inhibitor for three and two wk after transplantation, respectively.

RESULTS

After the first rituximab infusion, the peripheral blood CD19(+) B cell count rapidly decreased to <1%. All three patients treated with rituximab subsequently received an ABO-incompatible LDLT, with donor/recipient blood groups of B/O, A(1)/B and A(1)/O. In two cases, the ABO-antibody level transiently increased post-operatively, then decreased and remained low. Rituximab infusion therapy did not develop any direct side effect except for mild allergic reaction to the first infusion, but post-operatively all three patients suffered a cytomegalovirus and were successfully treated with ganciclovir, and one patient had a MRSA-positive intra-abdominal abscess. Two patients are currently alive at 20 and 18 months respectively, and show normal graft-liver function. But one patient died of sepsis because of intra-abdominal abscess.

CONCLUSIONS

Although the protocol of rituximab administration is a conventional and safe regimen with no major side effects, the development of a new protocol is needed for prevention of the infection with bone suppression.

Tolerance in Heart Transplantation: The Holy Grail, or an Attainable Goal?

The father of cardiac transplantation, Norman Shumway, famously predicted that tolerance was the future of the field, and always would be. Although his prediction remains true to date, significant progress has been made toward this goal, the "Holy Grail" for transplant clinicians. Current efforts are fueled by disappointing long-term outcomes associated with chronic immunosuppression, and the promise that partial or complete tolerance will impact long-term results favorably. This article provides a clinical definition of tolerance primarily based on lessons learned from animal heart allograft models. It reviews several promising strategies for inducing tolerance and detecting its presence through the use of biomarkers in peripheral blood or the graft, and outlines a possible path toward making this vision a clinical reality.

The emerging role of rituximab in organ transplantation

Long-term acceptance of solid organ allografts remains a challenge. While many acute rejection episodes can be treated, new mechanisms of allograft damage are now being defined especially in kidney transplantation. Unexpected clusters of CD20(+) cells have been discovered in renal biopsies performed for clinical rejection. C4d deposition is now routinely seen in refractory rejection. Despite the rapid introduction of new immunosuppressive agents in transplantation, the search for an efficacious anti-B-cell agent remains. With novel mechanisms of allograft damage now being defined, it is important to consider how an anti-B-cell agent might fit into an immunosuppressive regimen. Rituximab is a high-affinity CD20 specific antibody that depletes the B-cell compartment by inducing cellular apoptosis. Thus, it is a rational choice for therapy in transplantation to abrogate B-cell mediated events. In this review, we will discuss the mechanisms of action of rituximab, and its use in for a variety of indications in solid organ transplantation. There are emerging case reports that show that rituximab may be an effective agent to treat antibody-mediated rejection, and post-transplant lymphoproliferative disorder. Rituximab has been frequently cited as an important adjunct therapy in desensitization protocols for highly sensitized transplant recipients as well as recipients of ABO incompatible transplants. Rituximab demonstrates promise in this regard and warrants additional consideration in prospective clinical trials.

ABO-histo blood group incompatibility in hematopoietic stem cell and solid organ transplantation

In contrast to solid organ transplantation (SOT), ABO-histo blood group incompatibility is of minor importance for hematopoietic stem cell transplantation (HSCT). Patients receiving ABO-incompatible HSCT are at an increased risk for immune-mediated hematological complications including immediate and delayed hemolysis, late red blood cell engraftment and pure red cell aplasia, but seem not to have a worse overall survival or increased transplant-related mortality. This review gives an overview of the immunological mechanisms leading to complications associated with ABO-incompatible HSCT and describes approaches to prevent them. The current organ shortage in SOT stimulates the exploration of new strategies to expand the donor pool including ABO-incompatible SOT and xenotransplantation. Here, we discuss the hypothesis that ABO-incompatible transplantation may be viewed as a human in vivo model for the humoral immune mechanisms of antigen-mismatched transplantation. ABO-incompatible HSCT and SOT provide excellent possibilities to analyze graft accommodation and transplantation tolerance. Understanding the underlying mechanisms of graft survival in ABO-incompatible transplantation may facilitate new strategies to overcome the immunological barriers in SOT and xenotransplantation.

Lung Transplantation: Current Status and Challenges

The lung is an anatomically complex vital organ whose normal physiology depends on actively regulated ventilation and perfusion, and maintenance of a delicate blood-air barrier over a huge surface area in direct contact with a potentially hostile environment. Despite significant progress over the past 25 years, both short- and long-term outcomes remain significantly inferior for lung recipients relative to other "solid" organs. This review summarizes the current status of lung transplantation so as to frame the principle challenges currently facing end-stage lung-failure patients and the practitioners who care for them.

Characteristics of protein-carbohydrate interactions as a basis for developing novel carbohydrate-based antirejection therapies

The relative shortage of human organs for transplantation is today the major barrier to a broader use of transplantation as a means of treating patients with end-stage organ failure. This barrier could be partly overcome by an increased use of blood group ABO-incompatible live donors, and such trials are currently underway at several transplant centres. If xenotransplantation can be used clinically in the future, the human organ shortage will, in principle, be eradicated. In both these cases, carbohydrate antigens and the corresponding anti-carbohydrate antibodies are the major primary immunological barriers to overcome. Refined carbohydrate-based therapeutics may permit an increased number of ABO-incompatible transplantations to be carried out, and may remove the initial barriers to clinical xenotransplantation. Here, we will discuss the chemical characteristics of protein-carbohydrate interactions and outline carbohydrate-based antirejection therapies as used today in experimental as well as in clinical settings. Novel mucin-based adsorbers of natural anti-carbohydrate antibodies will also be described.

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.

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.

Soluble type A substance in fresh-frozen plasma as a function of ABO and Secretor genotypes and Lewis phenotype

Soluble ABO blood group substance (SAS) in fresh-frozen plasma (FFP) and its cognate alloantibody titer reduction capacity (TRC) are not considered when prescribing this product for plasma exchange (PEX) therapy of ABO incompatible transplant recipients. SAS was quantified in 250 single FFPs using ELISA. Total and IgG class-specific anti-A TRCs of FFPs were measured using a microhemagglutination inhibition assay. SAS level depended not only on the A subtype (p < 0.0001) and the Secretor status (p < 0.0001), but also on the expression of ALe(b) in A1 secretors (p < 0.0001). The variation was as great as 137.6 arbitrary units (aU) for 14 A1 Le(a-b-) secretors and 1.2 aU for 6 A2 non-secretors. Homozygous expression of the A1, A2 and Secretor alleles did not increase SAS levels. Only total anti-A TRC, but not IgG class-specific TRC depended on the detected SAS level (r = 0.566, p = 0.0003).

Management of an ABO-incompatible lung transplant

A 24-year-old woman with cystic fibrosis underwent bilateral sequential lung transplantation and unintentionally received an ABO incompatible graft (blood type A(1) graft into a type O recipient). The recipient had a high titer of IgG anti-A antibody (256 by the indirect antiglobulin test). Emergency treatment included antibody removal by plasmapheresis and additional immunosuppression with mycophenolate, rabbit antithymocyte globulin and polyspecific intravenous immunoglobulin. Subsequently, immunoadsorption and the anti-CD20 antibody rituximab were used to remove anti-A antibody and inhibit its resynthesis. Early graft function was good; one episode of rejection at Day 46 responded promptly to treatment with methylprednisolone. Subsequently, graft function continued to improve and anti-A antibody titers remained low. No infectious or other complications were encountered. The treatment regimen that we adopted may prove useful in other cases of unplanned ABO-incompatible organ transplants. The successful outcome suggests that planned ABO-incompatible lung transplants may be possible.

Excellent long-term outcome of ABO-incompatible living donor kidney transplantation in Japan

Owing to the severe shortage of cadaveric grafts in Japan, we have performed ABO-incompatible living donor kidney transplantation since 1989. This study assessed short- and long-term outcomes in 441 patients who received ABO-incompatible living donor kidney transplants between January 1989 and December 2001. We compared our results with historical data from 1055 recipients of living kidney transplantation. Overall patient survival rates 1, 3, 5, 7, and 9 years after ABO-incompatible transplantation were 93%, 89%, 87%, 85%, and 84%, respectively. Corresponding overall graft survival rates were 84%, 80%, 71%, 65%, and 59%. After ABO-incompatible transplantation, graft survival rates were significantly higher in patients 29 years or younger than in those 30 years or older and in patients who received anticoagulation therapy than in those who did not receive such therapy. There were no significant differences between A-incompatible and B-incompatible recipients with respect to clinical outcomes. The graft survival rate at 1 year in the historical controls was slightly but not significantly higher than that in our recipients of ABO-incompatible transplants. We conclude that long-term outcome in recipients of ABO-incompatible living kidneys is excellent. Transplantation of ABO-incompatible kidneys from living donors is a radical, but effective treatment for end-stage renal disease.

Switzerland is small in size but big on cardiology

Switzerland is a small country in the heart of Europe and well known worldwide for its Alps, foreign bank accounts, cheese, chocolate and watches. However, it also has made a significant contribution to cardiology, especially interventional cardiology. It was where balloon angioplasty and stenting of obstructed coronary arteries, two of the most stunning advances in cardiology in the last 30 years and the two most frequently performed interventional procedures in cardiology, originated. The author, who recently served as a visiting professor in the University of Geneva, University of Bern and University of Zurich, summarized his personal observations and impressions in this report.

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

Owing to the extreme shortage of cadaveric kidneys in Japan, ABO-incompatible kidney transplantation has been performed since 1989. We followed 441 recipients of ABO-incompatible kidney transplants. The long-term outcome did not differ significantly from that in recipients of living donor kidney transplants as a historic control group. Our data provide further evidence that humoral rejection due to ABO-antigen-antibody reaction does not occur once accommodation has been established. This report describes the characteristics of hyperacute and delayed hyperacute rejection as well as the mechanisms whereby accommodation is established in association with changes in donor (graft)-derived ABO histo-blood group glycosyltransferase, appearing in recipient blood after transplantation.

Living donor liver transplantation with special reference to ABO-incompatible grafts and small-for-size grafts

Living donor liver transplantation (LDLT) has developed on the basis of increased safety of conventional liver surgery and the need for expanding donor sources, especially in children. Indications for LDLT were soon extended to adult patients in Japan, where cadaveric donation was limited. The right liver is now routinely transplanted to adults to avoid small-for-size graft syndrome, even though the right liver graft has the disadvantages of less remaining donor liver and the question of donor safety. Assessing the suitable size or quality of the graft, as well as of the remnant donor liver, is one of the most important problems in adult LDLT. Although several tactics have been proposed to manage the small-for-size syndrome, their efficacy remains a question. We suggest that small-for-size syndrome is preventable by engaging in careful donor selection or using effective agents for hepatic microcirculatory disturbance control. Sometimes for LDLT only ABO-incompatible grafts are available from relatives, but they must be transplanted despite the expected poor outcome in adults and older children. To overcome the problems in this situation, we developed a novel protocol including intraportal infusion therapy with methylprednisolone, prostaglandin E1, and gabexate mesylate. Two adult patients undergoing ABO-incompatible LDLT have now survived 53 and 35 months after transplantation with good liver function. However, the other two patients suffered thrombotic microangiopathy postoperatively and died owing to cerebral hemorrhage or multiple organ failure, respectively. Further investigation is needed to improve the outcome of liver transplantation across the ABO blood group barrier.

Lung transplantation. Donor selection

The demand for donor lungs currently exceeds the supply of suitable grafts by a significant margin. Legal backgrounds and organizational and logistic issues are of major impact on the available donor pool. Re-evaluation of the donor criteria currently in use and new, innovative approaches such as living donor lung transplantation and non-heart-beating donation will hopefully contribute to improve this situation and reduce waiting time and waiting list mortality.