Successful combined partial auxiliary liver and kidney transplantation in highly sensitized cross-match positive recipients

National Trends and Outcomes of Combined Lung-Liver Transplantation: An Analysis of the UNOS Registry

PURPOSE

Combined lung-liver transplant (CLLT) is a complex yet life-saving procedure for patients with simultaneous end-stage lung and liver disease. Given the geographical allocation change to the lung allocation score (LAS) in 2017 and the recent SARS-CoV-2 outbreak in 2019, we aim to provide an updated analysis of the patient selection and outcomes of CLLTs.

METHODS

The UNOS registry was used to identify all patients who underwent CLLT between January 2014 and June 2023. To account for the changes made to LAS in 2017, baseline characteristics and outcomes were compared between era 1 (before 2017) and era 2 (after 2017). Risk factors for mortality were analyzed using the Cox regression hazard models. Recipient survival of up to 3 years was analyzed using the Kaplan-Meier method.

RESULTS

117 CLLTs were performed (77.8% in era 2). Donor organs experienced significantly longer ischemic times (p = 0.039) and traveled longer distances (p = 0.025) in era 2. However, recipient (p = 0.79) and graft (p = 0.41) survival remained comparable at up to 3 years post-transplant between eras. CLLTs demonstrated similar long-term survival to isolated lung transplants (p = 0.73). Higher recipient LAS was associated with an increased mortality risk (HR 1.14, p = 0.034). Recipient diagnosis of idiopathic pulmonary fibrosis carried a 5.03-fold risk of mortality (p = 0.048) compared to those with cystic fibrosis.

CONCLUSION

In the post-2017 LAS change era, CLLTs are increasingly performed with comparable outcomes to isolated lung transplants. A careful, multidisciplinary approach to patient selection and management remains paramount to optimizing outcomes for this rare patient population.

"No-donor" liver transplantation

Liver transplantation is hindered by organ shortage. The potential way to relieve this issue is to expand the donor pool via extending the donor criteria and make full use of all available grafts. The concept of "no-donor" liver transplantation allows grafts to be recovered from other liver recipients. This review summarizes the current clinical practice of "no-donor" liver transplantation, focusing on the experiences of Chinese transplant teams. Domino liver transplantation was introduced by Furtado in 1995 and implemented later in 2013 in China, and novel donor indications including some essential-to-treat inherited metabolic liver-based diseases have emerged. The concept of cross-auxiliary domino liver transplantation brings a further expansion of the domino liver graft pool, and the first pair of liver transplantation performed "rigorously without donation" was accomplished in our center in 2018. Our experience with this original transplantation procedure is hereby reviewed. In order to further promote and make successful "no-donor" liver transplantation, close co-operation between researchers, surgeons, physicians, organ procurement organizations, as well as ethical committees is required.

Simultaneous combined transplantation: Intricacies in immunosuppression management

Simultaneous combined transplantation (SCT), i.e. the transplantation of two solid organs within the same procedure, can be required when the patients develop more than one end-stage organ failure. The development of SCT over the last 20 years could only be possible thanks to progress in the surgical techniques and in the perioperative management of patients in an ageing population. Performing such major transplant surgeries from the same donor, in a short amount of time, and in critical pathophysiological conditions, is often considered to be counterbalanced by the immune benefits expected from these interventions. However, SCT includes a wide array of different transplant combinations, with each time a different immunological constellation. Recent research offers new insights into the immune mechanisms involved in these different settings. Progress in the understanding of these immunological intricacies help to address the optimal induction and maintenance immunosuppressive treatment strategies. In this review, we summarize the different immunological benefits according to the type of SCT performed. We also incorporate the main outcomes according to the immunological risk at transplantation, and the deleterious impact of preformed or de novo donor-specific antibodies (DSA) in the different types of SCT. Finally, we propose comprehensive and evidence-based induction and maintenance immunosuppression strategies guided by the type of SCT.

Comparison of cardiac allograft vasculopathy incidence between simultaneous multiorgan and isolated heart transplant recipients in the United States

BACKGROUND

Prior studies have shown reduced development of cardiac allograft vasculopathy (CAV) in multiorgan transplant recipients. The aim of this study was to compare the incidence of CAV between isolated heart transplants and simultaneous multiorgan heart transplants in the contemporary era.

METHODS

We utilized the Scientific Registry of Transplant Recipients to perform a retrospective analysis of first-time adult heart transplant recipients between January 1, 2010 and December 31, 2019 in the United States. The primary end-point was the development of angiographic CAV within 5 years of follow-up.

RESULTS

Among 20,591 patients included in the analysis, 1,279 (6%) underwent multiorgan heart transplantation (70% heart-kidney, 16% heart-liver, 13% heart-lung, and 1% triple-organ), and 19,312 (94%) were isolated heart transplant recipients. The average age was 53 years, and 74% were male. There were no significant between-group differences in cold ischemic time. The incidence of acute rejection during the first year after transplant was significantly lower in the multiorgan group (18% vs 33%, p < 0.01). The 5-year incidence of CAV was 33% in the isolated heart group and 27% in the multiorgan group (p < 0.0001); differences in CAV incidence were seen as early as 1 year after transplant and persisted over time. In multivariable analysis, multiorgan heart transplant recipients had a significantly lower likelihood of CAV at 5 years (hazard ratio = 0.76, 95% confidence interval: 0.66-0.88, p < 0.01).

CONCLUSIONS

Simultaneous multiorgan heart transplantation is associated with a significantly lower long-term risk of angiographic CAV compared with isolated heart transplantation in the contemporary era.

Combined Organ Transplantation in Patients with Advanced Liver Disease

Transplantation of the liver in combination with other organs is an increasingly performed procedure. Over the years, continuous improvement in survival could be realized through careful patient selection and refined organ preservation techniques, in spite of the challenges posed by aging recipients and donors, as well as the increased use of steatotic liver grafts. Herein, we revisit the epidemiology, allocation policies in different transplant zones, indications, and outcomes with regard to simultaneous organ transplants involving the liver, that is combined heart-liver, liver-lung, liver-kidney, and multivisceral transplantation. We address challenges surrounding combined organ transplantation such as equity, utility, and logistics of dual organ implantation, but also advantages that come along with combined transplantation, thereby focusing on molecular mechanisms underlying immunoprotection provided by the liver to the other allografts. In addition, the current standing and knowledge of machine perfusion in combined organ transplantation, mostly based on center experience, will be reviewed. Notwithstanding all the technical advances, shortage of organs, and the lack of universal eligibility criteria for certain multi-organ combinations are hurdles that need to be tackled in the future.

Detailed Analysis of Simultaneous Renal and Liver Allografts in the Presence of DSA

Liver allografts protect renal allografts from the same donor from some, but not all, preformed donor specific alloantibodies (DSA). However, the precise mechanisms of protection and the potential for more subtle alterations/injuries within the grafts resulting from DSA interactions require further study.

Methods

We reevaluated allograft biopsies from simultaneous liver-kidney transplant recipients who had both allografts biopsied within 60 d of one another and within 30 d of DSA being positive in serum (positive: mean florescence intensity ≥5000). Routine histology, C4d staining, and specialized immunohistochemistry for Kupffer cells (KCs; CD163) and a C4d receptor immunoglobulin-like transcript-4 were carried out in 4 patients with 6 paired biopsies.

Results

Overt antibody-mediated rejection was found in 3 of 4 renal and liver allografts. One patient had biopsy-confirmed renal and liver allograft antibody-mediated rejection despite serum clearance of DSA. All biopsies showed KC hypertrophy (minimal: 1; mild: 2; moderate: 1; severe: 2) and cytoplasmic C4d KC staining was easily detected in 2 biopsies from 2 patients; minimal and negative in 2 biopsies each. Implications of which are discussed. Control 1-y protocol liver allograft biopsies from DSA- recipients showed neither KC hypertrophy nor KC C4d staining (n = 6).

Conclusions

Partial renal allograft protection by a liver allograft from the same donor may be partially mediated by phagocytosis/elimination of antibody and complement split products by KCs, as shown decades ago in controlled sensitized experimental animal experiments.

Successful combined auxiliary partial liver and intestinal transplantation in two highly sensitized, cross-match positive patients

INTRODUCTION

Sensitization to human leukocyte antigen (HLA) creates an immunological barrier to intestinal transplantation (ITx). Current desensitization therapies are limited and ineffective in the most highly sensitized patients. A co-transplanted whole liver transplant can protect a kidney, heart, or intestinal allograft from antibody-mediated injury. Whether an auxiliary partial liver allograft provides effective protection for highly sensitized intestinal transplant recipients is unknown.

METHODS

Two patients with strong HLA donor-specific antibody at high titer against their deceased donors underwent combined auxiliary partial liver and ITx across a positive cross-match. The left lateral lobes from the combined-graft recipients and the right liver lobes from the deceased donors were transplanted as a domino procedure to other four patients.

RESULTS

Two combined-graft recipients have had an uneventful postoperative course without major complications at a 12- and 24-month follow-up, respectively. Intestinal graft function has been excellent with no evidence of humoral or cellular rejection. While a positive cross-match turned negative, titers of donor-specific HLA antibodies gradually declined over time after transplant. The left liver lobes procured from the combined-graft recipients were successfully transplanted into two pediatric patients (age 1.9, 2.4 years) and the right lobes from two deceased donors were successfully transplanted into two adult patients. All transplant procedures went well, without post-operative complications related to the splitting technique.

CONCLUSION

Our results indicate that an auxiliary liver transplant can effectively protect a co-transplanted intestinal allograft against rejection and suggest that this combined procedure may serve as a useful therapeutic adjunct for a highly sensitized intestinal transplant candidate.

Immunology of simultaneous liver and kidney transplants with identification and prevention of rejection

Simultaneous liver and kidney (SLK) transplantation is considered the best treatment modality among selected patients with both chronic kidney disease (CKD) and end-stage liver disease (ESLD). Since the first SLK transplant in 1983, the number of SLK transplants has increased worldwide, and particularly in the United States since the implementation of the MELD system in 2002. SLK transplants are considered a relatively low immunological risk procedure evidenced by multiple studies displaying the immunomodulatory properties of the liver on the immune system of SLK recipients. SLK recipients demonstrate lower rates of both cellular and antibody-mediated rejection on the kidney allograft when compared to kidney transplant-alone recipients. Therefore, SLK transplants in the setting of preformed donor-specific HLA antibodies (DSA) are a common practice, at many centers. Acceptance and transplantation of SLKs are based solely on ABO compatibility without much consideration of crossmatch results or DSA levels. However, some studies suggest an increased risk for rejection for SLK recipients transplanted across high levels of pre-formed HLA DSA. Despite this, there is no consensus regarding acceptable levels of pre-formed DSA, the role of pre-transplant desensitization, splenectomy, or immunosuppressive management in this unique population. Also, the impact of post-transplant DSA monitoring on long-term outcomes is not well-studied in SLK recipients. In this article, we review recent and relevant past articles in this field with a focus on the immunological risk factors among SLK recipients, and strategies to mitigate the negative outcomes among them.

Long-term outcomes of crossmatch positive simultaneous liver-kidney transplantations in the United States

The long-term outcomes of positive crossmatch (+XM) simultaneous liver-kidney (SLK) transplantations are conflicting. We examined the association between crossmatch status and SLK outcomes in recipients discharged on tacrolimus and mycophenolate with or without steroids. We analyzed the Scientific Registry of Transplant Recipients for all primary SLK recipients between 2003 and 2020 with available crossmatch and induction data. We grouped recipients according to the crossmatch status: negative crossmatch (-XM; n = 3040) and +XM (n = 407). Kaplan-Meier curves were generated to examine recipient, death-censored liver, and death-censored kidney survival by crossmatch status. Cox proportional hazard models were used to investigate the association between crossmatch status and outcomes of interest with follow-up censored at 10 years. Models were adjusted for recipient age, sex, diabetes mellitus, Model for End-Stage Liver Disease score, duration on the liver waiting list, induction immunosuppression, steroid maintenance, hepatitis C infection, donor age and sex, local vs. shared organ, cold ischemia time, and previous liver transplantation status. In the univariable analysis, crossmatch status was not associated with recipient survival (log-rank p = 0.63), death-censored liver graft survival (log-rank p = 0.05), or death-censored kidney graft survival (log-rank p = 0.11). Compared with -XM, +XM recipients had a similar 1-year liver rejection rate, but higher kidney rejection rate (4.6% vs. 8.9%, p = 0.002). In the multivariable models, +XM status was not associated with deleterious long-term recipient, liver, or kidney grafts survival. -XM and +XM SLK transplantations have comparable long-term recipient, liver graft, and kidney survival with a slightly increased risk of early kidney allograft rejection in the +XM group. Crossmatch positivity in SLK transplantations should not influence the decision to use organs from a specific donor.

Incidence of acute rejection and patient survival in combined heart-liver transplantation

Combined heart-liver transplantation (CHLT) is indicated for patients with concomitant end-stage heart and liver disease or patients with amyloid heart disease where liver transplantation mitigates progression. Limited data suggest that the liver allograft provides immunoprotection for heart and kidney allografts in combined transplantation from the same donor. We hypothesized that CHLT reduces the incidence of acute cellular rejection (ACR) and the development of de novo donor-specific antibodies (DSAs) compared with heart-alone transplantation (HA). We conducted a retrospective analysis of 32 CHLT and 280 HA recipients in a single-center experience. The primary outcome was incidence of ACR based on protocol and for-cause myocardial biopsy. Rejection was graded by the International Society of Heart and Lung Transplantation guidelines with Grade 2R and higher considered significant. Secondary outcomes included the development of new DSAs, cardiac function, and patient and cardiac graft survival rates. Of CHLT patients, 9.7% had ACR compared with 45.3% of HA patients (p < 0.01). Mean pretransplant calculated panel reactive antibody (cPRA) levels were similar between groups (CHLT 9.4% vs. HA 9.5%; p = 0.97). Among patients who underwent testing, 26.9% of the CHLT and 16.7% of HA developed DSA (p = 0.19). Despite the difference in ACR, patient and cardiac graft survival rates were similar at 5 years (CHLT 82.1% vs. HA 80.9% [p = 0.73]; CHLT 82.1% vs. HA 80.9% [p = 0.73]). CHLT reduced the incidence of ACR in the cardiac allograft, suggesting that the liver offers immunoprotection against cellular mechanisms of rejection without significant impacts on patient and cardiac graft survival rates. CHLT did not reduce the incidence of de novo DSA, possibly portending similar long-term survival among cardiac allografts in CHLT and HA.

First in Poland Simultaneous Liver-Lung Transplantation With Liver-First Approach for Recipient Due to Cystic Fibrosis: A Case Report

Cystic fibrosis is an autosomal progressive disease affecting the lung, pancreas, and liver. Some patients develop end-stage respiratory and liver failure. For such patients, combined lung-liver transplantation remains the only therapeutic option. In this article we present the first simultaneous lung-liver transplantation in Poland, as well as in Central and Eastern Europe, with detailed clinical history, surgical aspects, and postoperative course.

Current and Evolving Indications for Simultaneous Liver Kidney Transplantation

This review will discuss the etiologies of kidney disease in liver transplant candidates, provide a historical background of the prior evolution of simultaneous liver-kidney (SLK) transplant indications, discuss the current indications for SLK including Organ Procurement and Transplantation Network policies and Model for End Stage Liver Disease exception points, as well as provide an overview of the safety net kidney transplant policy. Finally, the authors explore unanswered questions and future research needed in SLK transplantation.

The Utility of Donor-specific Antibody Monitoring and the Role of Kidney Biopsy in Simultaneous Liver and Kidney Recipients With De Novo Donor-specific Antibodies

BACKGROUND

There is limited information about the utility of donor-specific antibody (DSA) against HLA monitoring and the role of protocol kidney biopsy for de novo DSA (dnDSA) in simultaneous liver and kidney (SLK) transplant recipients.

METHODS

We analyzed SLK transplant recipients transplanted between January 2005 and December 2017, who had DSA checked posttransplant. Patients were divided into 2 groups based on whether they developed dnDSA posttransplant (dnDSA+) or not (dnDSA-). Kidney graft rejection ±45 d of dnDSA and a kidney death-censored graft survival were the primary endpoints.

RESULTS

A total of 83 SLK transplant recipients fulfilled our selection criteria. Of those, 23 were dnDSA+ and 60 were dnDSA-. Twenty-two of 23 dnDSA+ patients had DSA against class II HLA, predominantly against DQ. Fifteen recipients underwent kidney biopsy ±45 d of dnDSA. Six of these were clinically indicated due to kidney graft dysfunction. The other 9 had a protocol kidney biopsy only due to dnDSA, and 6 of these 9 had a rejection. Also, 3 recipients had sequential biopsies of both the kidney and liver grafts. Among those with sequential biopsies of both grafts, there was a difference between the organs in the rate and types of rejections. At last follow up, dnDSA was not associated with graft failure of either the kidney or liver.

CONCLUSIONS

Although our study was limited by a small sample size, it suggests the potential utility of DSA monitoring and protocol kidney biopsy for dnDSA.

Heart-After-Liver Transplantation Attenuates Rejection of Cardiac Allografts in Sensitized Patients

BACKGROUND

In patients undergoing heart transplantation, significant allosensitization limits access to organs, resulting in longer wait times and high waitlist mortality. Current desensitization strategies are limited in enabling successful transplantation.

OBJECTIVES

The purpose of this study was to describe the cumulative experience of combined heart-liver transplantation using a novel heart-after-liver transplant (HALT) protocol resulting in profound immunologic protection.

METHODS

Reported are the results of a clinical protocol that was instituted to transplant highly sensitized patients requiring combined heart and liver transplantation at a single institution. Patients were dual-organ listed with perceived elevated risk of rejection or markedly prolonged waitlist time due to high levels of allo-antibodies. Detailed immunological data and long-term patient and graft outcomes were obtained.

RESULTS

A total of 7 patients (age 43 ± 7 years, 86% women) with high allosensitization (median calculated panel reactive antibody = 77%) underwent HALT. All had significant, unacceptable donor specific antibodies (DSA) (>4,000 mean fluorescence antibody). Prospective pre-operative flow cytometric T-cell crossmatch was positive in all, and B-cell crossmatch was positive in 5 of 7. After HALT, retrospective crossmatch (B- and T-cell) became negative in all. DSA fell dramatically; at last follow-up, all pre-formed or de novo DSA levels were insignificant at <2,000 mean fluorescence antibody. No patients experienced >1R rejection over a median follow-up of 48 months (interquartile range: 25 to 68 months). There was 1 death due to metastatic cancer and no significant graft dysfunction.

CONCLUSIONS

A heart-after-liver transplantation protocol enables successful transplantation via near-elimination of DSA and is effective in preventing adverse immunological outcomes in highly sensitized patients listed for combined heart-liver transplantation.

Intra-operative kinetics of anti-HLA antibody in simultaneous liver-kidney transplantation

During simultaneous liver-kidney transplantation (SLK) in highly sensitized patients, donor specific anti-human leukocyte antigen antibodies (DSA, HLA) can be present prior to transplant leading to positive crossmatch, yet these recipients have relatively low incidences of acute rejection. The mechanisms and timing underlying immunologic changes that occur intra-operatively remain largely unknown. Therefore, we measured the intra- and peri-operative kinetics of anti-HLA antibodies in highly sensitized SLK recipients. In this study, pre- and post-operative blood samples were obtained from sensitized SLK candidates with documented DSA. Intra-operative samples were obtained from a sub-group of SLK recipients. Pretransplant anti-HLA antibody profiles were created and flow cytometry and anti-human globulin complement-dependent cytotoxic crossmatches were performed. Significant reductions in anti-HLA class I and II DSA were seen intra-operatively shortly after reperfusion of the liver allograft. This effect was most pronounced for anti-HLA class I DSA (mean change, −85%, p < 0.05); changes to anti-HLA class II DSA were less robust (mean change, −47%, p = 0.15). Importantly, non-DSA anti-HLA antibodies remained unchanged throughout the perioperative period, suggesting the mechanism(s) by which the liver lowers DSA levels are specific to the DSA. These data demonstrate the immunologic benefit of performing SLK is lasting and occurs very shortly after liver reperfusion.

Kidney Rejection Following Simultaneous Liver-kidney Transplantation

BACKGROUND

Donor-specific antibodies are reported to increase the risk of rejection and reduce allograft survival following simultaneous liver-kidney transplantation. Optimal immunosuppression regimens to reduce this risk and to treat rejection episodes are underinvestigated.

METHODS

Cohort analysis of the first 27 simultaneous liver-kidney transplant recipients, between 2014 and 2018 at our unit, is performed under a new risk stratification policy. Those with donor-specific antibodies to class II HLA with a mean fluorescence intensity >10 000 are considered high risk for antibody-mediated rejection (AMR). These patients received immunosuppression, which consisted of induction therapy, tacrolimus, mycophenolate mofetil, and prednisolone. All other patients are considered low risk and received tacrolimus and prednisolone alone.

RESULTS

Three patients were high risk for rejection, and 2 of these patients developed AMR, which was treated with plasma exchange and intravenous immunoglobulin. At 1 y, their estimated glomerular filtration rate (eGFR) were 50 and 59 mL/min. Two other patients developed AMR, which was similarly treated, and their 1-y eGFR was 31 and 50 mL/min. The overall histologically proven acute rejection rate within the first year was 33%, and median eGFR, for the 27 patients, at 1 y was 52 mL/min and at 2 y was 49 mL/min.

CONCLUSIONS

This study confirms that there is a risk of AMR following simultaneous liver-kidney transplantation despite increased immunosuppression. This can be effectively treated with plasma exchange and intravenous immunoglobulin.

Kidney Graft Outcomes in High Immunological Risk Simultaneous Liver-Kidney Transplants

Recipients of simultaneous liver-kidney transplantations (SLKTs) have a lower risk of rejection compared with recipients of kidney transplants alone. However, there is disagreement about the impact of pretransplant anti-human leukocyte antigen sensitization on patient and kidney graft survival in the long term. The aim of the study was to evaluate the impact of the recipient immunological risk and comorbidities in renal graft outcomes on SLKT. We reviewed the SLKTs performed in our center from May 1993 until September 2017. Patient and graft survival were analyzed according to the immunological risk, comorbidities, liver and kidney rejection episodes, immunosuppression, and infections. A total of 20 recipients of SLKT were considered in the high immunological risk (HIR) group, and 68 recipients were included in the low immunological risk (LIR) control group. The prevalence of hepatitis C virus infection, second renal transplant, and time on dialysis prior to transplantation were significantly higher in the HIR group. The incidence of acute kidney rejection was higher in the HIR group (P<0.01). However, death-censored kidney graft survival as well as the estimated glomerular filtration rate at follow-up were not different between the 2 groups. Comorbidities, but not the immunological risk, impact negatively on patient survival. Despite the higher incidence of rejection in the HIR SLKT group, longterm renal function and graft survival were similar to the LIR group.

Association between post-transplant donor-specific antibodies and recipient outcomes in simultaneous liver-kidney transplant recipients: single-center, cohort study

There is a dearth of published data regarding the presence of post-transplant donor-specific antibodies (DSA), especially C1q-binding DSA (C1q+DSA), and patient and kidney allograft outcomes in simultaneous liver-kidney transplant (SLKT) recipients. We conducted a retrospective cohort study consisted of 85 consecutive SLKT patients between 2009 and 2018 in our center. Associations between presence of post-transplant DSA, including persistent and/or newly developed DSA and C1q+DSA, and all-cause mortality and the composite outcome of mortality, allograft kidney loss, and antibody-mediated rejection were examined using unadjusted and age and sex-adjusted Cox proportional hazards and time-dependent regression models. The mean age at SLKT was 56 years and 60% of the patients were male. Twelve patients (14%) had post-transplant DSA and seven patients (8%) had C1q+DSA. The presence of post-transplant DSA was significantly associated with increased risk of mortality (unadjusted model: Hazard Ratio (HR) = 2.72, 95% confidence interval (CI): 1.06-6.98 and adjusted model: HR = 3.20, 95% CI: 1.11-9.22) and the composite outcome (unadjusted model: HR = 3.18, 95% CI: 1.31-7.68 and adjusted model: HR = 3.93, 95% CI: 1.39-11.10). There was also higher risk for outcomes in recipients with C1q+DSA compared the ones without C1q+DSA. Post-transplant DSA is significantly associated with worse patient and kidney allograft outcomes in SLKT. Further prospective and large cohort studies are warranted to better assess these associations.

Lack of Association between Pretransplant Donor-Specific Antibodies and Posttransplant Kidney Outcomes in Simultaneous Liver-Kidney Transplant Recipients with Rabbit Anti-Thymocyte Globulin Induction and Steroid-Free Protocol

INTRODUCTION AND OBJECTIVE

The impact of pretransplant donor-specific antibodies (DSAs), especially class II DSAs, on kidney allograft outcomes remains unclear in simultaneous liver-kidney transplantation (SLKT) recipients.

METHODS

We examined 85 recipients who consecutively underwent SLKT between 2009 and 2018 in our center. Associations between pretransplant DSA and worsening kidney function (WKF), kidney allograft loss, composite kidney outcome (WKF and/or antibody-mediated rejection and/or death-censored kidney allograft loss), death with functioning graft, and overall mortality were examined in survival analysis. WKF was defined as an eGFR decrease of 30% or greater from baseline, or 2 or more episodes of proteinuria, at least 90 days apart from each other.

RESULTS

The mean age at SLKT was 56 ± 10 years, and 62% of the recipients were male. More than one quarter (26%) of our recipients were African American. The 2 major causes of end-stage liver disease were hepatitis C (28%) and alcoholic hepatitis (26%). Nineteen recipients (22%) had pretransplant DSAs at the time of SLKT. The DSA(+) group and DSA(-) group had similar risk of WKF (unadjusted model: hazard ratio [HR] = 0.77, 95% confidence interval [CI]: 0.29-2.05 and adjusted model: HR = 0.36, 95% CI: 0.12-1.08); similar risk of composite kidney outcome (unadjusted model: HR = 1.04, 95% CI: 0.45-2.43 and adjusted model: HR = 0.53, 95% CI: 0.20-1.39); and similar risk of overall death (unadjusted model: HR = 1.23, 95% CI: 0.45-3.36 and adjusted model: HR = 1.28, 95% CI: 0.42-3.87). We found similar results when comparing different DSA subclasses (class I and II DSAs) with recipients without DSAs.

CONCLUSIONS

The presence of pretransplant DSAs was not associated with worse kidney allograft outcomes from our single-center experience. Further prospective larger studies are strongly warranted.

The Role of Complement in Liver Injury, Regeneration, and Transplantation

The liver is both an immunologically complex and a privileged organ. The innate immune system is a central player, in which the complement system emerges as a pivotal part of liver homeostasis, immune responses, and crosstalk with other effector systems in both innate and adaptive immunity. The liver produces the majority of the complement proteins and is the home of important immune cells such as Kupffer cells. Liver immune responses are delicately tuned between tolerance to many antigens flowing in from the alimentary tract, a tolerance that likely makes the liver less prone to rejection than other solid organ transplants, and reaction to local injury, systemic inflammation, and regeneration. Notably, complement is a double-edged sword as activation is detrimental by inducing inflammatory tissue damage in, for example, ischemia-reperfusion injury and transplant rejection yet is beneficial for liver tissue regeneration. Therapeutic complement inhibition is rapidly developing for routine clinical treatment of several diseases. In the liver, targeted inhibition of damaged tissue may be a rational and promising approach to avoid further tissue destruction and simultaneously preserve beneficial effects of complement in areas of proliferation. Here, we argue that complement is a key system to manipulate in the liver in several clinical settings, including liver injury and regeneration after major surgery and preservation of the organ during transplantation.

Revisiting the liver's role in transplant alloimmunity

The transplanted liver can modulate the recipient immune system to induce tolerance after transplantation. This phenomenon was observed nearly five decades ago. Subsequently, the liver's role in multivisceral transplantation was recognized, as it has a protective role in preventing rejection of simultaneously transplanted solid organs such as kidney and heart. The liver has a unique architecture and is home to many cells involved in immunity and inflammation. After transplantation, these cells migrate from the liver into the recipient. Early studies identified chimerism as an important mechanism by which the liver modulates the human immune system. Recent studies on human T-cell subtypes, cytokine expression, and gene expression in the allograft have expanded our knowledge on the potential mechanisms underlying immunomodulation. In this article, we discuss the privileged state of liver transplantation compared to other solid organ transplantation, the liver allograft's role in multivisceral transplantation, various cells in the liver involved in immune responses, and the potential mechanisms underlying immunomodulation of host alloresponses.

Donor-specific hypo-responsiveness occurs in simultaneous liver-kidney transplant recipients after the first year

Kidney allografts of patients who undergo simultaneous liver-kidney transplantation incur less immune-mediated injury, and retain better function compared to other kidney allografts. To characterize the host alloimmune responses in 28 of these patients, we measured the donor-specific alloresponsiveness and phenotypes of peripheral blood cells after the first year. These values were then compared to those of 61 similarly immunosuppressed recipients of a solitary kidney or 31 recipients of liver allografts. Four multicolor, non-overlapping flow cytometry protocols were used to assess the immunophenotypes. Mixed cell cultures with donor or third party cells were used to measure cell proliferation and interferon gamma production. Despite a significant overlap, simultaneous liver-kidney transplant recipients had a lower overall frequency of circulating CD8+, activated CD4+ and effector memory T cells, compared to solitary kidney transplant recipients. Simultaneous liver-kidney transplant recipient T cells had a significantly lower proliferative response to the donor cells compared to solitary kidney recipients (11.9 vs. 42.9%), although their response to third party cells was unaltered. The frequency of interferon gamma producing alloreactive T cells in simultaneous liver-kidney transplant recipients was significantly lower than that of solitary kidney transplant recipients. Flow cytometric analysis of the mixed cultures demonstrated that both alloreactive CD4+ and CD8+ compartments of the simultaneous liver-kidney transplant recipient circulating blood cells were smaller. Thus, the phenotypic and functional characteristics of the circulating blood cells of the simultaneous liver-kidney transplant recipients resembled those of solitary liver transplant recipients, and appear to be associated with donor-specific hypo-alloresponsiveness.

Biomarkers of immune tolerance in liver transplantation

The liver exhibits intrinsic immune tolerogenic properties that contribute to a unique propensity toward spontaneous acceptance when transplanted, both in animal models and in humans. Thus, in contrast to what happens after transplantation of other solid organs, several years following liver transplantation a significant subset of patients are capable of maintaining normal allograft function with histological integrity in the absence of immunosuppressive drug treatment. Significant efforts have been put into identifying sensitive and specific biomarkers of tolerance in order to stratify liver transplant recipients according to their need for immunosuppressive medication and their likelihood of being able to completely discontinue it. These biomarkers are currently being validated in prospective clinical trials of immunosuppression withdrawal both in Europe and in the United States. These studies have the potential to transform the clinical management of liver transplant recipients by mitigating, at least in part, the burden of lifelong immunosuppression.

Application and interpretation of histocompatibility data in liver transplantation

PURPOSE OF REVIEW

There has been a resurgence of interest in histocompatibility as it applies to liver transplantation. The association of persistent and de-novo donor specific antibody (DSA) and outcomes after liver transplantation continues to be investigated.

RECENT FINDINGS

Consensus continues to evolve regarding the existence of acute and chronic antibody-mediated rejection (AMR) and pathogenicity of DSA and associated pathologic findings after liver transplantation. The presence of persistent high level, complement fixing DSA or emergence of de novo, Class II DSA has been associated with rejection and worse long-term graft and patient survival. Significant adverse associations of DSA extend to patients after simultaneous liver kidney (SLK) transplant as well as in pediatric recipients of liver transplantation. A higher degree of HLA incompatibility has been recently associated with worse outcomes in living donor liver transplant.

SUMMARY

In summary, recent consensus guidelines describe and recognize the existence of acute and chronic AMR and provide a basis upon which to build further investigation. Important adverse outcomes including decreased survival, allograft failure and liver fibrosis have been linked to the presence of DSA. Routine donor and recipient HLA typing and DSA assessment will facilitate diagnosis and provide for baseline data, which may help guide future management. Future investigations may help to clarify the role of therapeutic interventions.

Liver-inclusive intestinal transplantation results in decreased alloimmune-mediated rejection but increased infection

Background and aims

A co-transplanted liver allograft has been thought to protect other organs from rejection-mediated injury; however, detailed analyses of co-transplanted liver on intestinal allograft outcomes have not been conducted to date. The aim of the study was to compare immune-mediated injury, causes of graft failure and clinical outcomes between recipients who underwent either a liver-inclusive intestinal transplant (LITx) or liver-exclusive intestinal transplant (LETx).

Methods

Between May 2000 and May 2010, 212 adult patients undergoing LITx (n =76) and LETx (n =136) were included. LITx underwent either liver combined intestinal or full multivisceral transplantation. LETx underwent either isolated intestinal or modified multivisceral transplantation.

Results

During 44.9 ± 31.4 months of follow-up, death-censored intestinal graft survival was significantly higher for LITx than LETx (96.9%, 93.2% and 89.9% vs 91.4%, 69.3% and 60.0% at 1, 3 and 5 years; p =0.0001). Incidence of graft loss due to rejection was higher in LETx than in LITx (30.9% vs 6.6%; p <0.0001), while infection was the leading cause of graft loss due to patient death in LITx (25.0% vs 5.1%; p <0.0001). Despite similar immunosuppression, the average number (0.87 vs 1.42, p =0.02) and severity of acute cellular rejection episode (severe grade: 7.9% vs 21.3%; p =0.01) were lower in LITx than in LETx. Incidence of acute antibody-mediated rejection was also significantly lower in LITx than in LETx (3.6% vs 15.2%; p =0.03). Incidence of chronic rejection was reduced in LITx (3.9% vs 24.3%; p =0.0002).

Conclusions

Intestinal allografts with a liver component appear to decrease risk of rejection but increase risk of infection. Our findings emphasize that LITx has characteristic immunologic and clinical features. Lower immunosuppression may need to be considered for patients who undergo LITx to attenuate increased risk of infection.

Simultaneous liver-kidney transplantation: shifting renal allograft gene expression from inflammation toward preservation

Exposure of renal allografts to donor-specific antibodies activates many proinflammatory genes, resulting in antibody-mediated rejection. Simultaneous liver transplantation reduces the development of antibody-mediated rejection in renal grafts exposed to donor-specific antibodies. A study by Taner et al. in this issue of Kidney International shows this effect of the liver to involve more than simply absorbing donor-specific antibodies, with a shift in the pattern of gene expression in the kidney away from proinflammatory toward preservation of tissue function.

Utility in Treating Kidney Failure in End-Stage Liver Disease With Simultaneous Liver-Kidney Transplantation

Background

Simultaneous liver-kidney (SLK) transplantation plays an important role in treating kidney failure in patients with end-stage liver disease. It used 5% of deceased donor kidney transplanted in 2015. We evaluated the utility, defined as posttransplant kidney allograft lifespan, of this practice.

Methods

Using data from the Scientific Registry of Transplant Recipients, we compared outcomes for all SLK transplants between January 1, 1995, and December 3, 2014, to their donor-matched kidney used in kidney-alone (Ki) or simultaneous pancreas kidney (SPK) transplants. Primary outcome was kidney allograft lifespan, defined as the time free from death or allograft failure. Secondary outcomes included death and death-censored allograft failure. We adjusted all analyses for donor, transplant, and recipient factors.

Results

The adjusted 10-year mean kidney allograft lifespan was higher in Ki/SPK compared with SLK transplants by 0.99 years in the Model for End-stage Liver Disease era and 1.71 years in the pre-Model for End-stage Liver Disease era. Death was higher in SLK recipients relative to Ki/SPK recipients: 10-year cumulative incidences 0.36 (95% confident interval 0.33-0.38) versus 0.19 (95% confident interval 0.17-0.21).

Conclusions

SLK transplantation exemplifies the trade-off between the principles of utility and medical urgency. With each SLK transplantation, about 1 year of allograft lifespan is traded so that sicker patients, that is, SLK transplant recipients, are afforded access to the organ. These data provide a basis against which benefits derived from urgency-based allocation can be measured.

This analysis of the UNOS data demonstrated that SLK patients had decreased long term renal graft function that SPK patients. This analysis demonstrates the difficult policy choices epitomized by prioritizing the SLK population and its impact of utility considerations. Supplemental digital content is available in the text.

Pig Liver Xenotransplantation: A Review of Progress Toward the Clinic

Experience with clinical liver xenotransplantation has largely involved the transplantation of livers from nonhuman primates. Experience with pig livers has been scarce. This brief review will be restricted to assessing the potential therapeutic impact of pig liver xenotransplantation in acute liver failure and the remaining barriers that currently do not justify clinical trials. A relatively new surgical technique of heterotopic pig liver xenotransplantation is described that might play a role in bridging a patient with acute liver failure until either the native liver recovers or a suitable liver allograft is obtained. Other topics discussed include the possible mechanisms for the development of the thrombocytopenis that rapidly occurs after pig liver xenotransplantation in a primate, the impact of pig complement on graft injury, the potential infectious risks, and potential physiologic incompatibilities between pig and human. There is cautious optimism that all of these problems can be overcome by judicious genetic manipulation of the pig. If liver graft survival could be achieved in the absence of thrombocytopenia or rejection for a period of even a few days, there may be a role for pig liver transplantation as a bridge to allotransplantation in carefully selected patients.

Unique molecular changes in kidney allografts after simultaneous liver-kidney compared with solitary kidney transplantation

Kidney allografts transplanted simultaneously with liver allografts from the same donor are known to be immunologically privileged. This is especially evident in recipients with high levels of donor-specific anti-HLA antibodies. Here we investigated the mechanisms of liver's protective impact using gene expression in the kidney allograft. Select solitary kidney transplant or simultaneous liver-kidney transplant recipients were retrospectively reviewed and separated into four groups: 16 cross-match negative kidney transplants, 15 cross-match positive kidney transplants, 12 cross-match negative simultaneous liver-kidney transplants, and nine cross-match-positive simultaneous liver-kidney transplants. Surveillance biopsies of cross-match-positive kidney transplants had increased expression of genes associated with donor-specific antigens, inflammation, and endothelial cell activation compared to cross-match-negative kidney transplants. These changes were not found in cross-match-positive simultaneous liver-kidney transplant biopsies when compared to cross-match-negative simultaneous liver-kidney transplants. In addition, simultaneously transplanting a liver markedly increased renal expression of genes associated with tissue integrity/metabolism, regardless of the cross-match status. While the expression of inflammatory gene sets in cross-match-positive simultaneous liver-kidney transplants was not completely reduced to the level of cross-match-negative kidney transplants, the downstream effects of donor-specific anti-HLA antibodies were blocked. Thus, simultaneous liver-kidney transplants can have a profound impact on the kidney allograft, not only by decreasing inflammation and avoiding endothelial cell activation in cross-match-positive recipients, but also by increasing processes associated with tissue integrity/metabolism by unknown mechanisms.

Combined Kidney Transplantation and Splenic Fossa Auxiliary Heterotopic Liver Transplantation in a Highly Sensitized Recipient: A Case Report

BACKGROUND

Combined kidney and auxiliary orthotopic liver transplantation from the same donor is used to treat highly sensitized renal transplant recipients. Auxiliary liver can protect the transplanted kidney against hyperacute rejection.

METHODS

In the current case, combined kidney and splenic fossa auxiliary heterotopic liver transplantation was performed from the same donor for a highly sensitized recipient without preoperative preconditioning. No postoperative hyperacute rejection occurred.

RESULTS

Seven days after surgery, preexisting antibody levels rose and decreased after treatment; meanwhile, the function of transplanted kidney returned to normal. During 24 months of follow-up, the grafts showed good blood perfusion and functioned well. The levels of preexisting antibodies, donor-specific antibodies (DSA) and C1q-fixing human leukocyte antigen (C1q-HLA) antibodies, all decreased.

CONCLUSIONS

Combined kidney and splenic fossa auxiliary heterotopic liver transplantation can be used in renal transplantation for highly sensitized recipients.

Simultaneous liver kidney transplantation and (bilateral) nephrectomy through a midline is feasible and safe in polycystic disease

In Eurotransplant, 50% of simultaneous liver kidney transplantations (SLK) are performed for polycystic disease. Classically, liver and kidney are transplanted in two steps: liver through a subcostal incision, kidney through a separate oblique incision. Liver and kidney volume can make this 'two-step' procedure challenging, especially if simultaneous native nephrectomy is indicated. A 'one-step' SLK through a xiphopubic laparotomy might be a safe alternative, facilitating mobilization of the voluminous polycystic liver and native nephrectomy whilst offering access to iliac fossae for kidney transplantation. One-step SLK procedures for polycystic disease were introduced in 08/2013 at IKEM Prague (n = 6) and 11/2014 at University Hospitals Leuven (n = 6). Feasibility and safety of the one-step technique were investigated. We compared surgical data and outcomes obtained with the one-step technique to all consecutive two-step procedures performed for polycystic disease at the University Hospitals Leuven between 2008-2014 (n = 23). Median (interquartile range) are given. One-step SLK offered broad and adequate exposure for the hepatectomy, nephrectomies and transplantations, which were all uneventful. Morbidity, patient (100% vs 91%, p = 0.53) and graft survival (100% graft survival for liver and kidney in both groups) were comparable between one-step and two-step SLK. Liver cold ischaemia time was comparable [6.0 (4.4-7.6) vs. 7.1 (3.9-7.3), p = 0.077], kidney cold ischaemia time was shorter in one-step compared to two-step SLK [8.1 (6.4-9.3) vs. 11.7 (10.0-14.0), p<0.001)]. Total procedural time was also shorter in one-step compared to two-step SLK [6.8 (4.1-9.3) vs. 9.0 (8.7-10.1), p = 0.032], while all underwent bilateral (67%) or unilateral (33%) nephrectomy (compared to 0% and 52% in two-step SLK, respectively). In one-step SLK, 67% received a pre-emptive kidney transplant compared to 46% in two-step SLK. 5/12 two-step SLK became dialysis dependant after pre-transplant nephrectomy, the 4 dialysis-dependant patients with one-step SLK had not undergone pre-transplant nephrectomy. In conclusion, one-step SLK for polycystic disease is feasible and safe.

Five-year histological and serological follow-up of operationally tolerant pediatric liver transplant recipients enrolled in WISP-R

Pediatric liver transplant recipients arguably have the most to gain and the most to lose from discontinuing immunosuppression (IS). Whereas IS undoubtedly exerts a cumulative toll, there is concern that insufficient or no IS may contribute to allograft deterioration. Twelve pediatric recipients of parental living donor liver grafts, identified as operationally tolerant through complete IS withdrawal (WISP-R; NCT00320606), were followed for a total of 5 years (1 year of IS withdrawal and 4 years off IS) with serial liver tests and autoantibody and alloantibody assessments. Liver biopsies were performed 2 and 4 years off IS, and, at these time points, immunoglobulin G (IgG) subclass and C1q binding activity for donor-specific antibodies (DSAs) were determined. There were no cases of chronic rejection, graft loss, or death. Allografts did not exhibit progressive increase in inflammation or fibrosis. Smooth-muscle actin expression by stellate cells and CD34 expression by liver sinusoidal endothelial cells remained stable, consistent with the absence of progressive graft injury. Three subjects never exhibited DSA. However, 3 subjects showed intermittent de novo class I DSA, 4 subjects showed persistent de novo class II DSA, and 5 subjects showed persistent preexisting class II DSA. Class II DSA was predominantly against donor DQ antigens, often of high mean fluorescence intensity, rarely of the IgG3 subclass, and often capable of binding C1q.

CONCLUSION

Operationally tolerant pediatric liver transplant recipients maintain generally stable allograft histology in spite of apparently active humoral allo-immune responses. The absence of increased inflammation or progressive fibrosis suggests that a subset of liver allografts seem resistant to the chronic injury that is characteristic of antibody-mediated damage. (Hepatology 2017;65:647-660).

Everolimus and Advagraf Ab Initio in Combined Liver and Kidney Transplant With Donor-Specific Antibodies: A Case Report

Although donor-specific antibodies are regarded as a contraindication for kidney transplantation, the data available for combined liver and kidney transplantation (cLKTx) are scarce, and there is no established therapeutic approach for this category of transplant recipients. De novo use of everolimus and a reduced dose of calcineurin inhibitor reportedly provides excellent kidney function compared with a standard regimen containing a calcineurin inhibitor. This strategy, however, has been applied in only some recipient categories. Here we report a case of A highly sensitized male patient who underwent a cLKTx and received everolimus with low-dose tacrolimus (once-daily prolonged-release formulation) as ab initio immunosuppressive treatment. The pretransplant panel-reactive antibody estimate was 97%, and multiple anti-HLA antibodies were detected at the time of transplantation. Thus far, patient and allograft survival have reached 2 years, with the recipient remaining on a regimen of immunosuppression with everolimus and low-dose tacrolimus, with no episodes of rejection.

2016 Comprehensive Update of the Banff Working Group on Liver Allograft Pathology: Introduction of Antibody-Mediated Rejection

The Banff Working Group on Liver Allograft Pathology reviewed and discussed literature evidence regarding antibody-mediated liver allograft rejection at the 11th (Paris, France, June 5-10, 2011), 12th (Comandatuba, Brazil, August 19-23, 2013), and 13th (Vancouver, British Columbia, Canada, October 5-10, 2015) meetings of the Banff Conference on Allograft Pathology. Discussion continued online. The primary goal was to introduce guidelines and consensus criteria for the diagnosis of liver allograft antibody-mediated rejection and provide a comprehensive update of all Banff Schema recommendations. Included are new recommendations for complement component 4d tissue staining and interpretation, staging liver allograft fibrosis, and findings related to immunosuppression minimization. In an effort to create a single reference document, previous unchanged criteria are also included.

Protecting the Kidney in Liver Transplant Recipients: Practice-Based Recommendations From the American Society of Transplantation Liver and Intestine Community of Practice

Both acute and chronic kidney disease are common after liver transplantation and result in significant morbidity and mortality. The introduction of the Model for End-stage Liver Disease score has directly correlated with an increased prevalence of perioperative renal dysfunction and the number of simultaneous liver-kidney transplantations performed. Kidney dysfunction in this population is typically multifactorial and related to preexisting conditions, pretransplantation renal injury, perioperative events, and posttransplantation nephrotoxic immunosuppressive therapies. The management of kidney disease after liver transplantation is challenging, as by the time the serum creatinine level is significantly elevated, few interventions affect the course of progression. Also, immunological factors such as antibody-mediated kidney rejection have become of greater interest given the rising liver-kidney transplant population. Therefore, this review, assembled by experts in the field and endorsed by the American Society of Transplantation Liver and Intestine Community of Practice, provides a critical assessment of measures of renal function and interventions aimed at preserving renal function early and late after liver and simultaneous liver-kidney transplantation. Key points and practice-based recommendations for the prevention and management of kidney injury in this population are provided to offer guidance for clinicians and identify gaps in knowledge for future investigations.

Living donor liver transplantation in Europe

Living donor liver transplantation (LDLT) sparked significant interest in Europe when the first reports of its success from USA and Asia were made public. Many transplant programs initiated LDLT and some of them especially in Germany and Belgium became a point of reference for many patients and important contributors to the advancement of the field. After the initial enthusiasm, most of the European programs stopped performing LDLT and today the overall European activity is concentrated in a few centers and the number of living donor liver transplants is only a single digit fraction of the overall number of liver transplants performed. In this paper we analyse the present European activities and highlight the European contribution to the advancement of the field of LDLT.

Decreased chronic cellular and antibody-mediated injury in the kidney following simultaneous liver-kidney transplantation

In simultaneous liver-kidney transplantation (SLK), the liver can protect the kidney from hyperacute rejection and may also decrease acute cellular rejection rates. Whether the liver protects against chronic injury is unknown. To answer this we studied renal allograft surveillance biopsies in 68 consecutive SLK recipients (14 with donor-specific alloantibodies at transplantation [DSA+], 54 with low or no DSA, [DSA-]). These were compared with biopsies of a matched cohort of kidney transplant alone (KTA) recipients (28 DSA+, 108 DSA-). Overall 5-year patient and graft survival was not different: 93.8% and 91.2% in SLK, and 91.9% and 77.1% in KTA. In DSA+ recipients, KTA had a significantly higher incidence of acute antibody-mediated rejection (46.4% vs. 7.1%) and chronic transplant glomerulopathy (53.6% vs. 0%). In DSA- recipients at 5 years, KTA had a significantly higher cumulative incidence of T cell-mediated rejection (clinical plus subclinical, 30.6% vs. 7.4%). By 5 years, DSA+ KTA had a 44% decline in mean GFR while DSA+SLK had stable GFR. In DSA- KTA, the incidence of a combined endpoint of renal allograft loss or over a 50% decline in GFR was significantly higher (20.4% vs. 7.4%). Simultaneously transplanted liver allograft was the most predictive factor for a significantly lower incidence of cellular (odds ratio 0.13, 95% confidence interval 0.06-0.27) and antibody-mediated injury (odds ratio 0.11, confidence interval 0.03-0.32), as well as graft functional decline (odds ratio 0.22, confidence interval 0.06-0.59). Thus, SLK is associated with reduced chronic cellular and antibody-mediated alloimmune injury in the kidney allograft.

Review of combined liver and kidney transplantation in children

In this review, we focused on CLKT with regard to indication, results, outcome, and future developments. PH1 is one of the most common diagnoses for adult and pediatric patients qualifying for CLKT. The other major indication for combined transplantation is ARPKD. CLKT appears to be superior to sequential liver and kidney transplantation in the majority of patients and overall results following CLKT are now good, even in small children. Clinical observations suggest that there is an immunological advantage of CLKT in comparison with isolated liver or kidney transplantation. More clinical studies are necessary to identify the best candidates for CLKT while the availability of donor organs is low.

Macrochimerism in Intestinal Transplantation: Association With Lower Rejection Rates and Multivisceral Transplants, Without GVHD

Blood chimerism has been reported sporadically among visceral transplant recipients, mostly in association with graft-vs-host disease (GVHD). We hypothesized that a higher degree of mixed chimerism would be observed in multivisceral (MVTx) than in isolated intestinal (iITx) and isolated liver transplant (iLTx) recipients, regardless of GVHD. We performed a longitudinal prospective study investigating multilineage blood chimerism with flow cytometry in 5 iITx and 4 MVTx recipients up to one year posttransplant. Although only one iITx patient experienced GVHD, T cell mixed chimerism was detected in 8 out of 9 iITx/MVTx recipients. Chimerism was significantly lower in the four subjects who displayed early moderate to severe rejection. Pre-formed high-titer donor-specific antibodies, bound in vivo to the circulating donor cells, were associated with an accelerated decline in chimerism. Blood chimerism was also studied in 10 iLTx controls. Among nonsensitized patients, MVTx recipients exhibited greater T and B cell chimerism than either iITx or iLTx recipients. Myeloid lineage chimerism was present exclusively among iLTx and MVTx (6/13) recipients, suggesting that its presence required the hepatic allograft. Our study demonstrates, for the first time, frequent T cell chimerism without GVHD following visceral transplantation and a possible relationship with reduced rejection rate in MVTx recipients.

Detecting the humoral alloimmune response: we need more than serum antibody screening

Whereas many techniques exist to detect HLA antibodies in the sera of immunized individuals, assays to detect and quantify HLA-specific B cells are only just emerging. The need for such assays is becoming clear, as in some patients, HLA-specific memory B cells have been shown to be present in the absence of the accompanying serum HLA antibodies. Because HLA-specific B cells in the peripheral blood of immunized individuals are present at only a very low frequency, assays with high sensitivity are required. In this review, we discuss the currently available methods to detect and/or quantify HLA-specific B cells, as well as their promises and limitations. We also discuss scenarios in which quantification of HLA-specific B cells may be of additional value, besides classical serum HLA antibody detection.