Acute Antibody-mediated Rejection Research Articles

Hepatitis C viremic lung transplantation to aviremic recipients: Comprehensive outcomes and post-transplant viremia.

Direct-acting antiviral (DAA) therapy has revolutionized solid organ transplantation by providing an opportunity to utilize organs from HCV-viremic donors. Though transplantation of HCV-viremic donor organs into aviremic recipients is safe in the short term, midterm data on survival and post-transplant complications is lacking. We provide a midterm assessment of complications of lung transplantation (LT) up to 2 years post-transplant, including patient and graft survival between HCV-viremic transplantation (D+) and HCV-aviremic transplantation (D-). This is a retrospective cohort study including 500 patients from 2018 to 2022 who underwent LT at our quaternary care institution. Outcomes of patients receiving D+ grafts were compared to those receiving D- grafts. Recipients of HCV antibody+ but PCR- grafts were treated as D- recipients. We identified 470 D- and 30 D+ patients meeting inclusion criteria. Crude mortality did not differ between groups (p=.43). Patient survival at years 1 and 2 did not differ between D+ and D- patients (p=.89, p=.87, respectively), and graft survival at years 1 and 2 did not differ between the two groups (p=.90, p=.88, respectively). No extrahepatic manifestations or fibrosing cholestatic hepatitis (FCH) occurred among D+ recipients. D+ and D- patients had similar rates of post-transplant chronic lung allograft rejection (CLAD) (p=6.7%vs. 12.8%, p=.3), acute cellular rejection (60.0%vs. 58.0%, p=.8) and antibody-mediated rejection (16.7%vs. 14.2%, p=.7). There is no difference in midterm patient or graft survival between D+ and D-LT. No extrahepatic manifestations of HCV occurred. No differences in any type of rejection including CLAD were observed, though follow-up for CLAD was limited. These results provide additional support for the use of HCV-viremic organs in selected recipients in LT.

Acute rejection post lung transplant.

To review what is currently known about the pathogenesis, diagnosis, treatment, and prevention of acute rejection (AR) in lung transplantation. Epigenomic and transcriptomic methods are gaining traction as tools for earlier detection of AR, which still remains primarily a histopathologic diagnosis. Acute rejection is a common cause of early posttransplant lung graft dysfunction and increases the risk of chronic rejection. Detection and diagnosis of AR is primarily based on histopathology, but noninvasive molecular methods are undergoing investigation. Two subtypes of AR exist: acute cellular rejection (ACR) and antibody-mediated rejection (AMR). Both can have varied clinical presentation, ranging from asymptomatic to fulminant ARDS, and can present simultaneously. Diagnosis of ACR requires transbronchial biopsy; AMR requires the additional measuring of circulating donor-specific antibody (DSA) levels. First-line treatment in ACR is increased immunosuppression (pulse-dose or tapered dose glucocorticoids); refractory cases may need antibody-based lymphodepletion therapy. First line treatment in AMR focuses on circulating DSA removal with B and plasma cell depletion; plasmapheresis, intravenous human immunoglobulin (IVIG), bortezomib, and rituximab are often employed.

(1397) - Eculizumab as Rescue Therapy for Severe Acute Antibody Mediated Rejection in Heart Transplant Recipients

(1397) - Eculizumab as Rescue Therapy for Severe Acute Antibody Mediated Rejection in Heart Transplant Recipients

WCN24-868 MicroRNAs as biomarkers of acute antibody-mediated rejection in renal transplant patients

WCN24-868 MicroRNAs as biomarkers of acute antibody-mediated rejection in renal transplant patients

Plasma miR-150-5p in Renal Transplant Recipients with Acute Antibody-Mediated Rejection.

Background: Rejection continues to be the main cause of renal graft loss. Currently, the gold standard for diagnosis is an allograft biopsy; however, because it is time-consuming, costly, and invasive, the pursuit of novel biomarkers has gained interest. Variation in the expressions of miRNAs is currently considered a probable biomarker for the diagnosis of acute rejection. This study aimed to determine whether miR-150-5p in serum is related to microvascular damage in patients with acute antibody-mediated rejection (ABMR). Methods: A total of 27 patients who underwent renal transplantation (RT) with and without ABMR were included in the study. We performed the quantification of hsa-miR-150-5p, hsa-miR-155, hsa-miR-21, hsa-miR-126, and hsa-miR-1 in plasma by RT-qPCR. The expressions between the groups and their correlations with the histological characteristics of the patients with ABMR were also investigated. Results: miR-150-5p significantly increased in the plasma of patients with rejection (p < 0.05), and the changes in miR-150-5p were directly correlated with microvascular inflammation in the allograft biopsies. Clinical utility was determined by ROC analysis with an area under the curve of 0.873. Conclusions: Our results show that the patients with RT with ABMR exhibited increased expression of miR-150-5p compared to patients without rejection, which could have clinical consequences, as well as probable utility in the diagnosis of ABMR, and bioinformatics may help in unraveling the molecular mechanisms underlying ABMR conditions.

Novel factors potentially initiating acute antibody-mediated rejection in pig kidney xenografts despite an efficient immunosuppressive regimen.

Antibody-mediated rejection (AMR) is a common cause of graft failure after pig-to-nonhuman primate organ transplantation, even when the graft is from a pig with multiple genetic modifications. The specific factors that initiate AMR are often uncertain. We report two cases of pig kidney transplantation into immunosuppressed baboons in which we identify novel factors associated with the initiation of AMR. In the first, membranous nephropathy was the initiating factor that was then associated with the apparent loss of the therapeutic anti-CD154 monoclonal antibody in the urine when severe proteinuria was present. This observation suggests that proteinuria may be associated with the loss of any therapeutic monoclonal antibody, for example, anti-CD154 or eculizumab, in the urine, resulting in xenograft rejection. In the second case, the sequence of events and histopathology tentatively suggested that pyelonephritis may have initiated acute-onset AMR. The association of a urinary infection with graft rejection has been well-documented in ABO-incompatible kidney allotransplantation based on the expression of an antigen on the invading microorganism shared with the kidney graft, generating an immune response to the graft. To our knowledge, these potential initiating factors of AMR in pig xenografts have not been highlighted previously.

Overcoming the Boundaries of Heart Warm Ischemia in Donation After Circulatory Death: The Padua Case

A 45 year old male obese patient with a previous history of repaired congenital heart disease developed worsening heart failure making heart transplantation listing mandatory. Unfortunately, due to his anthropometric measures, the search for a suitable brain-dead donor was unsuccessful. For this reason, he accepted to be enrolled in the controlled donation after circulatory death (cDCD) program. According to the Italian Law regulating death declaration after cardiac arrest (no-touch period of 20 minutes—one of the longest in the world), we faced a 34 minute cardiac asystole, after which the heart was recovered through a thoraco-abdominal normothermic regional perfusion excluding the epiaortic vessels. The heart was then preserved by means of cold static storage. Heart transplantation was performed successfully without any signs of primary graft failure. Postoperative endomyocardial biopsies were negative for acute cellular and antibody-mediated rejection. Furthermore, echocardiographic and cardiac magnetic resonance evaluation of the heart did not show any functional abnormalities. The patient was discharged on post-operative day (POD) #39 in good clinical conditions.

Heart Transplantation.

Heart transplantation (HTx) remains the last therapeutic resort for patients with advanced heart failure. The present work is a clinically focused review discussing current issues in heart transplantation. Several factors have been associated with the outcome of HTx, such as ABO and HLA compatibility, graft size, ischemic time, age, infections, and the cause of death, as well as imaging and laboratory tests. In 2018, UNOS changed the organ allocation policy for HTx. The aim of this change was to prioritize patients with a more severe clinical condition resulting in a reduction in mortality of people on the waiting list. Advanced heart failure and resistant angina are among the main indications of HTx, whereas active infection, peripheral vascular disease, malignancies, and increased body mass index (BMI) are important contraindications. The main complications of HTx include graft rejection, graft angiopathy, primary graft failure, infection, neoplasms, and retransplantation. Recent advances in the field of HTx include the first two porcine-to-human xenotransplantations, the inclusion of hepatitis C donors, donation after circulatory death, novel monitoring for acute cellular rejection and antibody-mediated rejection, and advances in donor heart preservation and transportation. Lastly, novel immunosuppression therapies such as daratumumab, belatacept, IL 6 directed therapy, and IgG endopeptidase have shown promising results.

The medical cost and outcome of desensitization protocol in kidney transplantation recipients with high immunological risks.

Kidney transplantation is a well-established alternative in renal replacement therapy. Compared with hemodialysis, low-immunological-risk kidney transplantation can reduce the medical treatment costs associated with end-stage renal disease. However, there are few reports on whether high-immunological-risk kidney transplantation reduces the financial burden on governments. We investigated the medical costs of high-immunological-risk kidney transplantation in comparison with the cost of hemodialysis in Japan. We compared the medical costs of high-immunological-risk kidney transplantation with those of hemodialysis. 15 patients who underwent crossmatch-positive and/or donor-specific antibody-positive kidney transplantations between 2020 and 2021 were enrolled in this study. The patients received intravenous immunoglobulin, plasmapheresis, and rituximab as desensitizing therapy. Acute antibody-mediated rejection was detected in nine (60%) recipients, while there were no indications of graft function deterioration during the follow-up. For each patient, the transplant hospitalization cost was 38 428 ± 8789 USD. However, the cumulative costs were 59 758 ± 10 006 USD and 79 781 ± 16 366 USD, at 12 and 24 months, respectively. Compared with hemodialysis (34 286 USD per year), high-immunological-risk kidney transplantation tends to be expensive in the first year, but the cost is likely to be lower than that of hemodialysis after 3 years. Although kidney transplantation is initially expensive compared with hemodialysis, the medical cost becomes advantageous after 3 years even in kidney transplant recipients with high immunological risk.

Efficacy of mTOR Inhibitors and Intravenous Immunoglobulin for Treatment of Polyoma BK Nephropathy in Kidney Transplant Recipients: A Biopsy-Proven Study.

We investigated the efficacy of a predetermined protocol that consisted of immunosuppressive drug reduction/withdrawal and intravenous immunoglobulin administration for the treatment of polyoma BK virus nephropathy. Patients with biopsy-proven polyoma BK virus nephropathy received a treatment regimen based on discontinuation of both calcineurin inhibitors and antiproliferative agents and switching to mTOR inhibitors accompanied by intravenous immunoglobulin administration. Our study included 508 patients, with polyoma BK viremia detected in 80 patients. The mean age was 45.3 ± 9.5 years (range, 18-71 y), 64% were male, and mean follow-up was 37 ± 21 months (6-94 mo). All 16 patients who developed polyoma BK virus nephropathy and 9 patients who had highgrade polyoma BK viremia without nephropathy received intravenous immunoglobulin treatment. Compared with patients with viremia, patients with polyoma BK virus nephropathy had significantly higher rates of graft loss due to rejection (18.8% vs 1.6%; P = .024) and all-cause graft loss (31.2% vs 6.3%; P = .014). Histopathologically, viral inclusion bodies disappeared and SV40 became negative after treatment in all 13 patients who underwent protocol biopsies. Unfortunately, histopathologically complete recovery without chronic tubular and interstitial tissue damage was achieved in only 4 patients after treatment. In addition, 3 patients lost their grafts due to acute antibody-mediated or mixed-type rejection (18.8%). In patients with polyoma BK virus nephropathy, clearance of viremia and SV40 should not be the sole outcomes to obtain. Aggressive reductions in maintenance immunosuppression and switching to double-drug therapy combined with high-dose intravenous immunoglobulin leads to high rates of graft loss/rejection and sequalae of chronic histological changes.

Identification of liver transplant biopsy phenotypes associated with distinct liver biological markers and allograft survival

The intricate association between histologic lesions and circulating antihuman leucocyte antigen donor-specific antibodies (DSA) in liver transplantation (LT) requires further clarification. We conducted a probabilistic, unsupervised approach in a comprehensively well-annotated LT cohort to identify clinically relevant archetypes. We evaluated 490 pairs of LT biopsies with DSA testing from 325 recipients transplanted between 2010 and 2020 across 3 French centers and an external cohort of 202 biopsies from 128 recipients. Unsupervised archetypal analysis integrated all clinico-immuno-histologic parameters of each biopsy to identify biopsy archetypes. The median time after LT was 1.17 (interquartile range, 0.38-2.38) years. We identified 7 archetypes distinguished by clinico-immuno-histologic parameters: archetype #1: severe T cell-mediated rejection (15.9%); #2: chronic rejection with ductopenia (1.8%); #3: architectural and microvascular damages (3.5%); #4: (sub)normal (55.9%); #5: mild T cell-mediated rejection (4.9%); #6: acute antibody-mediated rejection (6.5%); and #7: chronic rejection with DSA (11.4%). Cell infiltrates vary in the archetype. These archetypes were associated with distinct liver biological markers and allograft outcomes. These findings remained consistent when stratified using the patient’s age or indications for LT, with good performance in the external cohort (mean highest probability assignment = 0.58, standard deviation ± 0.17). In conclusion, we have identified clinically meaningful archetypes, providing valuable insights into the intricate DSA-histology association, which may help standardize liver allograft pathology classification.

Impact of Preformed Donor-Specific Anti-HLA-Cw and Anti-HLA-DP Antibodies on Acute Antibody-Mediated Rejection in Kidney Transplantation.

Given the risk of rejection, the presence of preformed donor specific antibodies (DSA) contraindicates transplantation in most allocation systems. However, HLA-Cw and -DP DSA escape this censorship. We performed a multicentric observational study, in which the objective was to determinate risk factors of acute antibody-mediated rejection (aABMR) in recipients transplanted with preformed isolated Cw- or DP-DSA. Between 2010 and 2019, 183 patients were transplanted with a preformed isolated Cw- or DP-DSA (92 Cw-DSA; 91 DP-DSA). At 2years, the incidence of aABMR was 12% in the Cw-DSA group, versus 28% in the DP-DSA group. Using multivariable Cox regression model, the presence of a preformed DP-DSA was associated with an increased risk of aABMR (HR = 2.32 [1.21-4.45 (p = 0.001)]) compared with Cw-DSA. We also observed a significant association between the DSA's MFI on the day of transplant and the risk of aABMR (HR = 1.09 [1.08-1.18], p = 0.032), whatever the DSA was. Interaction term analysis found an increased risk of aABMR in the DP-DSA group compared with Cw-DSA, but only for MFI below 3,000. These results may plead for taking these antibodies into account in the allocation algorithms, in the same way as other DSA.

The diagnosis of acute antibody-mediated rejection was delayed due to the initial suspicion of graft dysfunction caused by renal artery stenosis

The diagnosis of acute antibody-mediated rejection was delayed due to the initial suspicion of graft dysfunction caused by renal artery stenosis

Diagnostic significance of TGF-β1 in kidney recipients with graft dysfunction

Development of minimally invasive diagnosis techniques for complications in recipients, based on analysis of the levels of molecular and genetic biomarkers, is an urgent task facing modern transplantology. Transforming growth factor beta 1 (TGF-β1), which has multiple effects in the body, among the potential indicators of complications.Objective: to assess the diagnostic significance of serum TGF-β1 in kidney recipients with graft dysfunction.Materials and methods. The study included 129 kidney recipients aged 17 to 68 years and 35 healthy subjects. Serum TGF-β1 levels in the recipients were determined by immunoenzyme technique.Results. Kidney recipients included 95 patients with laboratory and clinical signs of graft dysfunction, who underwent biopsy of the transplanted kidney, followed by morphological examination, and 34 recipients with normal graft function. Serum TGF-β1 levels in the kidney recipients were significantly higher than in their healthy counterparts (p = 0.00001); it did not correlate with most blood test parameters; with the glomerular filtration rate (GFR). Kidney recipients with graft dysfunction had significantly higher TGF-β1 levels than other recipients (p = 0.018). In recipients with graft dysfunction, morphological study revealed the following: acute tubular necrosis (ATN, n = 11), acute T-cell mediated rejection (ACR, n = 26), acute antibody-mediated rejection (AMR, n = 35), non-immune-mediated nephrosclerosis with signs of calcineurin inhibitor nephrotoxicity (CNI nephrotoxicity, n = 13), and recurrent glomerulonephritis (chronic graft rejection, n = 10). Recipients with immune-mediated graft injury (ACR, AMR and chronic rejection) had higher serum TGF-β1 levels than recipients with graft dysfunction resulting from other causes, p &lt; 0.0001. Kidney recipients with serum TGF-β1 levels above the threshold value of 94.3 ng/mL had a higher risk of immune-mediated graft dysfunction than other kidney recipients (RR = 2.2 ± 0.22 [95% CI 1.46–3.46]) with 77.5% test sensitivity and 60.3% specificity.Conclusion. The calculated threshold serum TGF-β1 level in kidney recipients can be considered as an auxiliary indicator of graft dysfunction resulting from acute or chronic rejection.

Echocardiographic reference ranges for non-invasive myocardial work indices in heart transplant patients

Abstract Background Non-invasive myocardial work (MW) is a relatively novel echocardiographic method with increasing fields of application. Normal reference ranges of MW indices in a healthy population have already been determined but these may differ in patients who have undergone a heart transplant (HTX). Purpose To obtain the reference ranges for 2D echocardiographic indices of MW for HTX patients and to compare them with the results of the EACVI NORRE study regarding healthy volunteers. Methods All consecutive HTX patients admitted at our Institution under Day Hospital regimen from September 2019 to May 2022 who performed endomyocardial biopsy (EMB) were considered. Patients with echocardiographic exam or brachial artery cuff pressure unavailability, history of rejection, history of coronary artery vasculopathy (CAV) and either acute cellular rejection (ACR) or acute antibody-mediated rejection (AMR) at EMB were excluded. Non-invasive MW calculation through Speckle-tracking Echocardiography (STE) was retrospectively performed for included patients. Further, MW analysis results were compared to those from the EACVI NORRE study. Results Out of 176 HTX patients who had performed EMB and had available echocardiographic and blood pressure data, 35 patients were excluded because of history of rejection, 4 patients because of history of CAV and 55 patients because of either ACR or AMR at EMB. Therefore, study population consisted of 82 HTX patients (68.3% male, median age 53 (46 – 62) years). Median age from HTX was 5 (2 – 22) months. Mean global work efficiency (GWE, 84 ± 8 %), global work index (GWI, 1447 ± 409 mmHg%), global constructive work (GCW, 2067 ± 423 mmHg%) and median global wasted work (GWW, 310 (217 – 499) mmHg%) did not differ between sex categories (p-value &amp;gt; 0.05). Each of these indices significantly differed from those reported in the EACVI NORRE study (p-value &amp;lt; 0.001), with lower GWI, GCW, GWE and higher GWW in the HTX population. Conclusion This study provides reference ranges for non-invasive MW indices in a HTX population free from transplant-related complications which are different from those regarding a population of healthy volunteers.Table 1

Chronic Active Antibody-mediated Rejection: Opportunity to Determine the Role of Interleukin-6 Blockade.

Chronic active antibody-mediated rejection (caAMR) is arguably the most important cause of late kidney allograft failure. However, there are no US Food and Drug Administration (FDA)-approved treatments for acute or chronic AMR and there is no consensus on effective treatment. Many trials in transplantation have failed because of slow and/or inadequate enrollment, and no new agent has been approved by the FDA for transplantation in over a decade. Several lines of evidence suggest that interleukin-6 is an important driver of AMR, and clazakizumab, a humanized monoclonal antibody that neutralizes interleukin-6, has shown promising results in phase 2 studies. The IMAGINE trial (Interleukin-6 Blockade Modifying Antibody-mediated Graft Injury and Estimated Glomerular Filtration Rate Decline) (NCT03744910) is the first to be considered by the FDA using a reasonably likely surrogate endpoint (slope of estimated glomerular filtration rate decline >1 y) for accelerated approval and is the only ongoing clinical trial for the treatment of chronic rejection. This trial offers us the opportunity to advance the care for our patients in need, and this article is a call to action for all transplant providers caring for patients with caAMR.

A Urinary Proteomics Approach to Predict Treatment Response in Acute Antibody-Mediated Rejection

Acute antibody-mediated rejection (AMR) is a severe complication affecting kidney allografts' long-term survival. Timely detection and appropriate treatment of AMR are crucial for improving graft outcomes. This study aimed to discover non-invasive urinary biomarkers that can predict the response to therapy in patients with AMR. Materials and Methods: In this case-control study, urine samples from 21 biopsy-proven AMR patients underwent proteomics using label-free quantification. The patients were divided into two groups: responders and non-responders to treatment based on their graft function. Urinary proteins were identified, and their expressions were compared between the two groups to identify potential candidate biomarkers. Out of the 1020 identified proteins, 257 proteins were found to be differentially expressed between the two groups. Among these, 153 proteins showed increased expression in non-responder patients, while 104 proteins showed decreased expression. Non-responder patients exhibited higher activation of complement pathway and extracellular matrix degradation than responders. Insulin-like growth factor binding protein 6 (IGFBP-6) emerged as the most sensitive and specific biomarker for predicting non-response to treatment in patients with AMR. Our study has successfully identified urinary proteome biomarkers that can distinguish and predict non-responder patients with AMR. These biomarkers are associated with various biological processes that reflect the pathogenesis and severity of AMR. Further research is necessary to validate these findings.

Thrombotic microangiopathies after kidney transplantation in modern era: nosology based on chronology

BackgroundThrombotic microangiopathies (TMAs) are rare but can be severe in kidney transplant.recipients (KTR).MethodsWe analysed the epidemiology of adjudicated TMA in consecutive KTR during the.2009–2021 period.ResultsTMA was found in 77/1644 (4.7%) KTR. Early TMA (n = 24/77 (31.2%); 1.5% of all KTR) occurred during the first two weeks ((median, IQR) 3 [1–8] days). Triggers included acute antibody-mediated rejection (ABMR, n = 4) and bacterial infections (n = 6). Graft survival (GS) was 100% and recurrence rate (RR) was 8%. Unexpected TMA (n = 31/77 (40.2%); 1.5/1000 patient-years) occurred anytime during follow-up (3.0 (0.5–6.2) years). Triggers included infections (EBV/CMV: n = 10; bacterial: n = 6) and chronic active ABMR (n = 5). GS was 81% and RR was 16%. Graft-failure associated TMA (n = 22/77 (28.6%); 2.2% of graft losses) occurred after 8.8 (4.9–15.5) years). Triggers included acute (n = 4) or chronic active (n = 14) ABMR, infections (viral: n = 6; bacterial: n = 5) and cancer (n = 6). 15 patients underwent transplantectomy. RR was 27%. Atypical (n = 6) and typical (n = 2) haemolytic and uremic syndrome, and isolated CNI toxicity (n = 4) were rare. Two-third of biopsies presented TMA features.ConclusionsTMA are mostly due to ABMR and infections; causes of TMA are frequently combined. Management often is heterogenous. Our nosology based on TMA timing identifies situations with distinct incidence, causes and prognosis.

Belatacept and carfilzomib-based treatment for antibody-mediated rejection in a sensitized nonhuman primate kidney transplantation model

IntroductionOne-third of HLA-incompatible kidney transplant recipients experience antibody mediated rejection (AMR) with limited treatment options. This study describes a novel treatment strategy for AMR consisting of proteasome inhibition and costimulation blockade with or without complement inhibition in a nonhuman primate model of kidney transplantation.MethodsAll rhesus macaques in the present study were sensitized to maximally MHC-mismatched donors by two sequential skin transplants prior to kidney transplant from the same donor. All primates received induction therapy with rhesus-specific ATG (rhATG) and were maintained on various immunosuppressive regimens. Primates were monitored postoperatively for signs of acute AMR, which was defined as worsening kidney function resistant to high dose steroid rescue therapy, and a rise in serum donor-specific antibody (DSA) levels. Kidney biopsies were performed to confirm AMR using Banff criteria. AMR treatment consisted of carfilzomib and belatacept for a maximum of four weeks with or without complement inhibitor.ResultsTreatment with carfilzomib and belatacept was well tolerated and no treatment-specific side effects were observed. After initiation of treatment, we observed a reduction of class I and class II DSA in all primates. Most importantly, primates had improved kidney function evident by reduced serum creatinine and BUN as well as increased urine output. A four-week treatment was able to extend graft survival by up to two months.DiscussionIn summary, combined carfilzomib and belatacept effectively treated AMR in our highly sensitized nonhuman primate model, resulting in normalization of renal function and prolonged allograft survival. This regimen may translate into clinical practice to improve outcomes of patients experiencing AMR.

Feasibility of Interleukin-6 Receptor Blockade in Cardiac Antibody-mediated Rejection.

Antibody-mediated rejection (AMR) remains a significant cause of heart transplant mortality with few effective therapies. This study aimed to describe initial experience of using interleukin-6 receptor blockade with tocilizumab in the treatment of acute cardiac AMR at Barnes-Jewish Hospital/Washington University Transplant Center from July 2017 to May 2021 (n = 7). Clinical, echocardiographic, and serum alloantibody data were analyzed before and after treatment. All participants demonstrated marked improvement in functional status. Echocardiographic data following 4-6 mo of tocilizumab revealed significant improvements in biventricular systolic function for all participants. Consistent reductions in donor-specific HLA or angiotensin type I receptor antibodies were not observed, suggesting that tocilizumab may act downstream of antibody production. No patient experienced drug-related complications that necessitated discontinuation of therapy. These findings provide initial insights into the safety and efficacy of interleukin-6 receptor blockade in the treatment of cardiac AMR and support the design of larger prospective studies.