Circulating donor-specific anti-human leukocyte antigen antibodies and complement C4d deposition are associated with the development of cardiac allograft vasculopathy

BACKGROUND

Cardiac allograft vasculopathy (CAV) continues to be a limiting factor in long-term survival of heart transplant recipients (HTRs). Pathophysiologic and immunologic factors affecting CAV are complex, and criteria for early diagnosis remain elusive.

METHODS

We performed a retrospective analysis of the relationship between donor-specific antibody (DSA), C4d immunofluorescence, and the development of CAV.

RESULTS

We evaluated 330 endomyocardial biopsy (EMB) specimens from 112 cardiac grafts. Twenty-four (21%) of 112 grafts developed CAV, and 18 (75%) of 24 were positive for C4d. Patients with DSA (n = 51) against human leukocyte antigen class I (n = 5), II (n = 26), or both (n = 20) developed CAV at a rate of 40%, 38%, and 20% and a mean time to CAV of 89, 47, and 25 months, respectively. Of 61 grafts without DSA, only 13% developed CAV, with a mean time to CAV of 116 months.

CONCLUSIONS

Compared with the general HTR population, patients with graft dysfunction and DSA or positive C4d on EMB show a statistically significant increased incidence of CAV and allograft failure, suggesting an antibody-mediated injury. The presence of pre- and posttransplant DSA, even in the absence of positive C4d immunofluorescence, may identify a group of HTRs at increased risk of developing CAV.

Clinical significance of donor-specific human leukocyte antigen antibodies in liver transplantation

Antibody-mediated rejection (AMR) caused by donor-specific anti-human leukocyte antigen antibodies (DSA) is widely accepted to be a risk factor for decreased graft survival after kidney transplantation. This entity also plays a pathogenic role in other solid organ transplants as it appears to be an increasingly common cause of heart graft dysfunction and an emerging issue in lung transplantation. In contrast, the liver appears relatively resistant to DSA-mediated injury. This “immune-tolerance” liver property has been sustained by a low rate of liver graft loss in patients with preformed DSA and by the intrinsic liver characteristics that favor the absorption and elimination of DSA; however, alloantibody-mediated adverse consequences are increasingly being recognized, and several cases of acute AMR after ABO-compatible liver transplant (LT) have been reported. Furthermore, the availability of new solid-phase assays, allowing the detection of low titers of DSA and the refinement of objective diagnostic criteria for AMR in solid organ transplants and particularly in LT, have improved the recognition and management of this entity. A cost-effective strategy of DSA monitoring, avoidance of class II human leukocyte antigen mismatching, judicious immunosuppression attached to a higher level of clinical suspicion of AMR, particularly in cases unresponsive to conventional anti-rejection therapy, can allow a rational approach to this threat.

Acute antibody-mediated rejection after intestinal transplantation

AIM

To investigate the incidence, risk factors and clinical outcomes of acute antibody-mediated rejection (ABMR) after intestinal transplantation (ITx).

METHODS

A retrospective single-center analysis was performed to identify cases of acute ABMR after ITx, based on the presence of donor-specific antibody (DSA), acute tissue damage, C4d deposition, and allograft dysfunction.

RESULTS

Acute ABMR was identified in 18 (10.3%) out of 175 intestinal allografts with an average occurrence of 10 d (range, 4-162) after ITx. All acute ABMR cases were presensitized to donor human leukocyte antigens class I and/or II antigens with a detectable DSA. A positive cross-match was seen in 14 (77.8%) cases and twelve of 18 patients (66.7%) produced newly-formed DSA following ITx. Histological characteristics of acute ABMR include endothelial C4d deposits, interstitial hemorrhage, and severe congestion with focal fibrin thrombin in the lamina propria capillaries. Multivariate analysis identified a liver-free graft and high level of panel reactive antibody as a significant independent risk factor. Despite initial improvement after therapy, eleven recipients (61.1%) lost transplant secondary to rejection. Of those, 9 (50%) underwent graft removal and 4 (22.2%) received second transplantation following acute ABMR. At an average follow-up of 32.3 mo (range, 13.3-76.4), 8 (44.4%) recipients died.

CONCLUSION

Our results indicate that acute ABMR is an important cause of intestine graft dysfunction, particularly in a liver-exclusive graft and survivors are at an increased risk of developing refractory acute rejection and chronic rejection. More effective strategies to prevent and manage acute ABMR are needed to improve outcomes.

The association between human leukocyte antigen eplet mismatches, de novo donor-specific antibodies, and the risk of acute rejection in pediatric kidney transplant recipients

BACKGROUND

The longitudinal relationship between HLA class I and II eplet mismatches, de novo donor-specific antibodies (dnDSA) development, and acute rejection after transplantation in childhood is unknown.

METHODS

Eplet mismatches at HLA class I and II loci were calculated retrospectively for each donor/recipient pair transplanted between 2005 and 2015 at a single Australian center. Logistic regression analyses were conducted to determine the association between the number of eplet mismatches, dnDSA, and acute rejection.

RESULTS

The cohort comprised 59 children (aged 0-18 years) who received their first kidney allograft and were followed for median (interquartile range) 4.5 (± 2.6) years. Overall, 32% (19/59) developed dnDSA (class I 3% (2/59), class II 14% (8/59), 15% class I and II (9/59)), and 24% (14/59) developed biopsy-proven acute rejection. Every unit increase in class I and II eplet mismatches corresponded to an increase in risk of class I (odds ratio (OR) 1.22, 95% CI 1.07-1.39, p < 0.01) and class II (OR 1.06, 95% CI 1.01-1.11, p = 0.02) dnDSA development. Compared with recipients without dnDSA, class I and II dnDSA were associated with direction of effect towards increased risk of acute cellular rejection (class I: OR 5.87, 95% CI 0.99-34.94, p = 0.05; class II: OR 12.00, 95% CI 1.25-115.36, p = 0.03) and acute antibody-mediated rejection (class I: OR 25.67, 95% CI 3.54-186.10, p < 0.01; class II: OR 9.71, 95% CI 1.64-57.72, p = 0.01).

CONCLUSIONS

Increasing numbers of HLA class I or II eplet mismatches were associated with the development of dnDSA. Children who developed dnDSA were also more likely to develop acute rejection compared with children without dnDSA.

Immunoadsorption Combined with Membrane Filtration to Counteract Early Treatment-Refractory Antibody-Mediated Rejection

INTRODUCTION

Immunoadsorption (IA) represents a therapeutic option for acute antibody-mediated rejection (ABMR) after kidney transplantation. The addition of membrane filtration (MF) to enhance elimination of macromolecular components that potentially contribute to rejection, such as key complement component C1q and alloreactive IgM, may be an effective strategy to further improve its therapeutic efficiency.

RESULTS

Here we present 4 consecutive patients with episodes of HLA donor-specific antibody-positive ABMR nonresponsive to cycles of 6-16 sessions of IA treatment. Rejection episodes were characterized by severe microvascular injury (high-grade microcirculation inflammation and/or signs of thrombotic microangiopathy) and evidence of intense complement activation in peritubular capillaries (diffuse C4d-positivity). IA combined with MF led to substantial morphologic improvement (follow-up biopsies: g + ptc and C4d scores ≤1) and stabilization of allograft function.

CONCLUSIONS

Our findings provide evidence for an effect of combination of IA + MF in refractory early acute/active ABMR in kidney transplant recipients.

Lung Transplant Pathology: An Overview on Current Entities and Procedures

Alloimmune reactions are, besides various infections, the major cause for impaired lung allograft function following transplant. Acute cellular rejection is not only a major trigger of acute allograft failure but also contributes to development of chronic lung allograft dysfunction. Analogous to other solid organ transplants, acute antibody-mediated rejection has become a recognized entity in lung transplant pathology. Adequate sensitivity and specificity in the diagnosis of alloimmune reactions in the lung can only be achieved by synoptic analysis of histopathologic, clinical, and radiological findings together with serologic and microbiologic findings.

Capillary leak syndrome as a complication of antibody-mediated rejection treatment: a case report

We report a case of capillary leak that developed during treatment of antibody-mediated rejection in a kidney transplant recipient. A 53-year-old female transplant recipient experienced an increase in serum creatinine from 1.1 to 1.8 mg/dL. Antibody-mediated rejection was diagnosed by graft biopsy. She was treated with five plasmapheresis sessions (on alternate days with albumin replacement), five doses of immunoglobulin (5 g/dose at 100 mg/kg), a single dose of rituximab (500 mg), and four doses of bortezomib on days 1, 4, 7, and 10 (1.72 mg/dose at 1.3 mg/m² body surface area). During treatment, edema, slight diarrhea, pancytopenia, hypoalbuminemia, peripheral neuropathy, and postural hypotension were noted. Despite control of liquids, she presented with edema progressing to an increase of more than 10 kg body weight. Prerenal acute graft dysfunction associated with hypotension was diagnosed on day 12, heart failure or other infectious complications being discounted. On day 13, daily hemodialysis was prescribed, and a stable volume status was reached after five hemodialysis sessions. On day 20, the patient recovered diuresis and the edema and diarrhea abated, but she remained on chronic hemodialysis. After excluding other causes of distributive shock, the diagnosis of capillary leak syndrome was based on the presence of hypotension, generalized edema, and hypoalbuminemia in the absence of significant proteinuria. The concomitant presence of diarrhea, peripheral neuropathy, and pancytopenia, suggest a possible causal role for bortezomib. Awareness by clinicians of capillary leak syndrome associated with bortezomib-based treatment of AMR is paramount, despite its rarity.

Early acute rejection after lung transplantation mimicking viral pneumonia in the middle of COVID-19 pandemic: A case report

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An atypical clinical presentation of early antibody-mediated rejection in COVID era.

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The radiological features mimicked SARS-CoV2 pneumonia, but tests were negative.

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This is the first report of lung transplantation in the COVID era in Europe.

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Decide whether to keep lung transplantation programmes open in a COVID Hospital.

Introduction

In addition to morbidity and mortality rate per se, COVID-19 outbreak leads to potential ‘side effects’, which are difficult to evaluate and predict. Lung transplantation is a consolidated treatment for end-stage chronic lung disease requiring significantly demanding management. Deciding whether to keep transplant programmes open during an epidemic of this size is not easy, as immunosuppressed subjects face the risk of infection and related mortality. Additionally, there is a chance for the patient’s standard care process to be compromised.

Presentation of case

We report the case of a patient undergoing bilateral lung transplantation during the explosion of COVID-19 epidemic in Lombardy; he died from definite early acute antibody-mediated rejection, clinically (persistent high fever, unresponsive to treatment) and radiologically mimicking viral pneumonia but persistently negative for SARS-CoV-2.

Discussion

The diagnosis was difficult given this atypical presentation, confounded by global scenario. Grafts were procured from a donation after circulatory death donor in an uncontrolled setting and a donor-recipient transmission was possible. Our institute became a COVID-Hospital right during the first post-transplantation days. Radiological imaging had the same features of SARS-CoV-2 pneumonia.

Conclusions

This is the first report of lung transplantation of the COVID-19 era in Europe. Our extremely fragile patient was COVID-19 free up to the end. Donor-recipient transmission is conceivable, but the risk should be assessed with respect to waiting list mortality. Ultimately, treating COVID-19 patients can be a resource-consuming activity but we decided to keep our centre open.

Efficacy of Double Membrane Filtration Immunoadsorption in Severe C1q-Binding Donor-Specific Antibody-Positive Acute Humoral Kidney Allograft Rejection: A Case Series

INTRODUCTION

Acute antibody-mediated rejection (ABMR) is an important threat to renal allograft survival in the early transplant period and the major single cause of graft loss in the first postoperative year. Semi-selective immunoadsorption (IA) remains one of the commonly applied treatments in ABMR, reducing allo-reactive antibody load. Adding double filtration plasmapheresis (DFPP) to IA might enhance therapeutic efficacy by also addressing innate humoral effectors like complement factors.

METHODS

Four patients with ABMR were treated with DFPP + IA. Clinical, histological, and immunological data and adverse events were retrospectively collected.

RESULTS

Here we present four high-risk treatment-refractory ABMR cases with C1q-binding donor-specific antibodies and histology of humoral rejection under treatment with DFPP + IA. While the earlier cases (within the first year after transplantation) showed marked reduction in ABMR severity and improvement of kidney function, the later cases did not respond accordingly. Late ABMR patient 1 stabilized, whereas late ABMR patient 2 did not respond to treatment.

CONCLUSIONS

Our data support the consideration of DFPP + IA as a rescue treatment option in early, severe, high-risk ABMR cases in which other treatments failed.