Humoral Rejection Research Articles

Management and long-term outcome of recurrent idiopathic FSGS in pediatric kidney transplant recipients

Focal segmental glomerulosclerosis (FSGS) is a major cause of pediatric kidney failure. Most cases of FSGS in children are idiopathic and have a high risk of post-transplantation recurrence and graft loss. Common treatments for recurrent FSGS (rFSGS) post-transplantation include plasmapheresis, immunoadsorption, and/or immunomodulatory therapy. This study retrospectively evaluated the efficacy and safety of early plasmapheresis followed by rituximab for inducing and maintaining remission in rFSGS. Between 2014 and 2023, 8 of 65 pediatric kidney transplant recipients at our center were diagnosed with idiopathic FSGS. rFSGS was diagnosed based on nephrotic range proteinuria with no other cause and managed with plasmapheresis. Rituximab therapy was used for those who did not achieve complete remission with prolonged plasmapheresis or remained plasmapheresis dependent. 6 of 8 (75%) transplant recipients with idiopathic FSGS experienced rFSGS. All patients achieved partial or complete remission with plasmapheresis, with response times ranging from 8 to 379 days (median 13 days). Rituximab therapy was introduced for 5 plasmapheresis-dependent patients, leading to sustained remission and cessation of plasmapheresis in 3 patients, while 2 showed improved proteinuria and reduced plasmapheresis frequency. Adverse effects included rituximab-induced serum sickness in one patient and one mild allergic reaction. One patient experienced graft loss due to humoral rejection, but no grafts were lost to rFSGS, and all other grafts remained functional over an average follow-up of 50 months. Early plasmapheresis followed by rituximab therapy effectively induces remission in most post-transplantation rFSGS cases, is well tolerated, and prevents graft loss. Larger studies are needed to confirm these findings.

How safe is lung transplantation in patients of 65 years or older? A single-center retrospective cohort

IntroductionWith increasing experience in high-volume centers, age alone should not be an absolute contra-indication to lung transplantation (LT) but be considered as part of the patient's initial characteristics. The objective of this study is to provide early and long-term outcomes of LT in recipients aged 65 or older, compared with their younger counterparts. MethodsThis is a retrospective study, including all patients undergoing LT in Bichat Hospital (Paris, France) from January 2014 to March 2019. Two groups were defined depending on the patients’ age when they were transplanted: patients older than 65 were defined as the “elderly group” and patients younger than 65 years old were defined as the « younger group ». Primary endpoint was 90-day mortality. Secondary endpoints included 1-year mortality, 1-year FEV1 (forced expiratory volume in one second), and 5-year overall survival. ResultsFrom September 2014 to March 2019, 22 patients were included in the “elderly group” and 213 were included in the « younger group ». The elderly group had more single LT (SLT) (82% vs. 29%, p < 0.001), with a shorter cold ischemic time (243 min vs. 310 min, p = 0.001) and a lower rate of early humoral rejection (9% vs. 30%, p = 0.045) compared to the younger group. Ninety-day mortality was not significantly different between elderly and younger group (9% vs. 14%, p = 0.95, respectively), nor were 1-year mortality (23% vs. 25%, p = 0.9, respectively) and 5-year overall survival. Six months after LT, FEV1 was significantly better in the elderly group compared to the younger group (77.0% vs. 65.5%, p = 0.037 respectively), but the difference did not reach statistical significance after one year (78.5 vs. 68.3%, p = 0.18 respectively). ConclusionElderly patients underwent more frequently single LT, and achieved similar short and long term postoperative outcomes compared to their younger counterparts. LT for patients 65 years or older should be routinely considered when carefully selected.

225.3: Randomized phase 2 trial of felzartamab in humoral transplant rejection.

225.3: Randomized phase 2 trial of felzartamab in humoral transplant rejection.

First experience in Mexico with plasmapheresis and rituximab treating humoral rejection in heart transplant

First experience in Mexico with plasmapheresis and rituximab treating humoral rejection in heart transplant

Chimeric HLA antibody receptor T cell therapy for humoral transplant rejection.

Antibody-mediated rejection (ABMR) is a significant obstacle to achieving optimal long-term outcomes after solid organ transplantation. The presence of donor-specific antibodies (DSA), particularly against HLA, increases the risk of allograft rejection and subsequent graft loss. No effective treatment of ABMR currently exists, warranting novel approaches to target the HLA-specific humoral alloimmune response. Cellular therapies may hold promise to this end. According to publicly available sources as of now, three independent laboratories have genetically engineered a chimeric HLA-antibody receptor (CHAR) and transduced it into human T cells, based on the demonstrated efficacy of chimeric antigen receptor T cell therapies in malignancies. These CHAR-T cells are designed to exclusively eliminate B cells that produce donor-specific HLA antibodies, which form the cornerstone of ABMR. CHAR technology generates potent and functional human cytotoxic T cells to target alloreactive HLA-specific B cells, sparing B cells with other specificities. Thus, CHAR technology may be used as a selective desensitization protocol and to treat antibody-mediated rejection after solid organ transplantation.

Клинический случай ортотопической трансплантации сердца с дальнейшим острым гуморальным отторжением трансплантата

Клинический случай ортотопической трансплантации сердца с дальнейшим острым гуморальным отторжением трансплантата

#715 Adiponectin / leptin ratio as an index to determine the risk of metabolic and rejection complications in patients after kidney transplantation

Abstract Background and Aims Adipose tissue, as an endocrine and paracrine organ, produces several hormones that are involved in the regulation of metabolic and inflammatory processes or immune system activity. While leptin is the main pro-inflammatory marker of adipose tissue, adiponectin is characterized by its anti-inflammatory effects. The adiponectin / leptin (A/L) ratio had been shown to correlate better with the occurrence of cardiometabolic risk factors than hormone concentrations alone. Results in the general population suggest that an A/L ratio &amp;gt; 1 can be considered normal, an A/L ratio of 0.5-1 indicates a moderate increase, and an A/L ration &amp;lt; 0.5 a high increase in cardiometabolic risk. The first aim of our study was to determine the risk of developing post-transplant diabetes mellitus (PTDM), prediabetes and other metabolic risk factors in relation to the A/L ratio in patients after kidney transplantation (KT). The second aim was to determine the risk of developing acute graft rejection in relation to the A/L ratio in patients after KT. Method A total of 104 patients were included in our prospective analysis after applying inclusion and exclusion criteria. Pre-transplantation and subsequently at 3, 6 and 12 months after KT, we recorded baseline characteristics of donors and recipients, including parameters characterizing graft function, metabolic (lipid profile, indices of glucose metabolism) and anthropometric parameters. At the same time, we examined serum adipocytokine concentrations (adiponectin, leptin) and calculated the A/L ratio. In the third month after KT, all patients underwent protocol graft biopsy and donor specific antibody (DSA) testing by Luminex method. Results We found that during the follow-up period, there was a significant increase in the A/L ratio in the control group (p = 0.0013) and, on the other hand, a significant decrease in the group who developed PTDM (p = 0.0003). Comparing the different subgroups divided on the A/L ratio one year after KT, we found that patients with an A/L &amp;lt; 0.5 were significantly longer in the dialysis program, had higher body mass index (BMI), waist circumference, worse graft function, and a higher prevalence of prediabetes and PTDM compared with those whose A/L ratio was &amp;gt; 1. Using logistic regression in multivariate analysis, we identified age at the time of KT [OR 1.0709, (p = 0.0337)], triglycerides level at 1 year after KT [OR 2.7735, (p = 0.446)] and A/L ratio &amp;lt; 0.5 [OR 3.1724, (p = 0.014)] as independent risk factors for the development of prediabetes and PTDM 1 year after KT. At the same time, after adjusting for differences in baseline donor and recipient characteristics, we identified the subgroup with an A/L ratio &amp;lt; 0.5 pre-transplant [HR 1.6126, (p = 0.0133)] and 3 months after KT [HR 1.3150, (p = 0.0172)] as an independent risk factor for the development of acute graft rejection. In the subsequent specification of the rejection episode, we found that A/L ratio &amp;lt; 0.5 pre-transplant [HR 2.2353, (p = 0.0357)] and 3 months after KT [HR 3.0954, (p = 0.0237)] is and independent risk factor for the occurrence of acute humoral rejection with DSA positivity. Conclusion In our study, we found that an A/L ratio &amp;lt; 0.5 is an independent risk factor for the development of prediabetes, PTDM 1 year after KT and acute humoral graft rejection with de novo DSA production in the third month after KT. This is the first study to investigate the correlation of the A/L ratio with the risk of developing metabolic and immunological complications in patients after KT.

#1315 Management and long-term outcome of recurrent idiopathic FSGS in pediatric renal transplant recipients

Abstract Background and Aims Focal segmental glomerulosclerosis (FSGS) is a leading cause of pediatric end-stage renal disease (ESRD). While approximately 30% of pediatric FSGS is attributed to monogenic disorders, most cases are idiopathic, carrying a high risk of post-transplantation recurrence and graft loss. Commonly used protocols for recurrent FSGS (rFSGS) include plasmapheresis or immunoadsorption, and/or immunomodulatory therapy. We retrospectively evaluated the efficacy and safety of early plasmapheresis followed by rituximab therapy for induction of remission in rFSGS. Method Between 2014-2023, 8/65 pediatric renal transplant recipients at our center were diagnosed with idiopathic FSGS. Five patients underwent preventive plasmapheresis initiated between day 7 pre-transplantation to day 1 post-transplantation, depending on donor source (living/deceased). rFSGS, was diagnosed based on nephrotic range proteinuria of no other cause, and managed with daily plasmapheresis, followed by frequency tapering. Failure to achieve complete remission while on prolonged plasmapheresis was managed with Rituximab therapy. Results 6/8 patients (75%) experienced rFSGS. All achieved partial or complete remission with plasmapheresis therapy. Nevertheless, 5/6 patients exhibited plasmapheresis-dependence, thereby necessitating rituximab therapy. Of these, 3/5 patients achieved sustained remission enabling plasmapheresis cessation, while in 2/5 showed markedly improved proteinuria, enabling reduction of plasmapheresis frequency to once weekly. Adverse effects included rituximab-induced serum sickness in one patient, requiring therapy discontinuation. While one patient suffered from graft loss due to humoral rejection, no graft was lost to rFSGS, and all other grafts remained functional over an average follow-up period of 50 months. Conclusion We suggest that early introduction of plasmapheresis and rituximab therapy effectively induces remission in most post-transplantation rFSGS, is well tolerated, and prevents graft loss. Additional, large scale studies are needed to establish our observation.

Management of immunosuppressive therapy after functional renal graft failure: results of a practice survey of French-speaking nephrologists

The management of patients with kidney transplant failure (KTF) remains a complex process involving multiple stakeholders. A working group of the Transplantation Commission of the French-speaking Society of Nephrology, Dialysis and Transplantation (SFNDT) conducted a survey on the management of immunosuppressants (IS) after KTF among nephrologists at transplant centres and general nephrologists in France, Switzerland and Belgium between March and June 2023. We analysed 232 replies from 58 nephrologists at transplant centres and 174 general nephrologists, aged 43.6 (+10.6) years. In the first three months following KTF, nephrologists reported discontinuing antimetabolite, calcineurin inhibitor (CNI) and corticosteroid treatment in 83%, 39.9% and 25.8% of cases respectively. Conversely, some nephrologists reported that they were continuing to use CNI (14%) and corticosteroids (19.1%) on a long-term basis. The patient’s comorbidities associated with the discontinuation of IS treatment are cancer and opportunistic infections as KT’s complications and presence of diabetes mellitus at KTF, whereas humoral rejection encourages the IS to be maintained. Transplantectomy is proposed by nephrologists most often for graft intolerance syndrome (86.5%), more rarely to discontinue IS (17.6%) or in the absence of plans of new transplantation (9.3%). In multivariate analyses, the presence of a protocol in the centre facilitated the management of IS by the general nephrologists. The management of IS after AFG by French-speaking nephrologists is heterogeneous. Specific prospective studies are needed to establish new best practice recommendations, based on more robust evidence, which could encourage better adherence by nephrologists.

First experience in Mexico with plasmapheresis and rituximab treating humoral rejection in heart transplant

First experience in Mexico with plasmapheresis and rituximab treating humoral rejection in heart transplant

Effect of Different Induction Immunosuppression on the Incidence of Infectious Complications after Kidney Transplantation-Single Center Study.

Background/Objectives: Potent immunosuppression lowers the incidence of acute graft rejection but increases the risk of infections. In order to decrease either infectious complications or acute rejection, it is necessary to identify risk groups of patients profiting from personalized induction immunosuppressive treatment. The aim of our analysis was to find whether there were higher incidences of infectious complications after kidney transplantation (KT) in groups with different induction immunosuppressive treatment and also to find independent risk factors for recurrent infections. Materials: We retrospectively evaluated all patients with induction treatment with basiliximab after kidney transplantation from 2014 to 2019 at our center relative to age- and sex-matched controls of patients with thymoglobulin induction immunosuppression. Results: Our study consisted of two groups: basiliximab (39) and thymoglobulin (39). In the thymoglobulin group we observed an increased incidence of recurrent infection in every observed interval; however, acute rejection was seen more often in the basiliximab group. A history of respiratory diseases and thrombocytopenia were identified as independent risk factors for recurrent bacterial infections from the first to sixth month after KT. Decreased eGFR from the first month, infections caused by multi-drug-resistant bacteria, and severe infections (reflected by the need for hospitalization) were identified as independent risk factors for recurrent bacterial infections from the first to the twelfth month after KT. Conclusions: We found that in the group of patients with thymoglobulin induction immunosuppressive treatment, infectious complications occurred significantly more often during the entire monitored period with decreased incidence of acute humoral and cellular rejection occurred more often.

(344) - Coexistence of Acute Cellular and Humoral Rejection in Heart Allograft: The Relationship with Circulating Antihla Antibodies

(344) - Coexistence of Acute Cellular and Humoral Rejection in Heart Allograft: The Relationship with Circulating Antihla Antibodies

Pretransplant Screening for Prevention of Hyperacute Graft Loss in Pig-to-primate Kidney Xenotransplantation.

Xenotransplantation using pig organs is now a clinical reality. However, the process for xenograft recipient screening lacks clarity and scientific rigor: no established thresholds exist to determine which levels of preformed antipig natural antibodies (Nabs) will be safe for clinical xenograft transplantation, and hyperacute rejection (HAR) or acute humoral xenograft rejection (AHXR), which still impacts pig-to-primate kidney xenograft survivals, may impede broader application of pig-to-human clinical xenograft transplantation. We retrospectively examined 28 cases of pig-to-baboon kidney xenotransplantation using GalTKO±human complement regulatory protein (hCRP)-transgenic (Tg) pig donors, as well as 6 cases of triple-KO multi-Tg (10GE) pig donors, and developed screening algorithms to predict risk of HAR/AHXR based on recipient antipig Nab levels. Preformed Nabs were evaluated using both complement-dependent cytotoxicity and antibody (IgM and IgG) binding flow-cytometry assays. High complement-dependent cytotoxicity was associated with HAR/AHXR as expected. However, we also found that high levels of IgG were independently associated with HAR/AHXR, and we developed 2 indices to interpret and predict the risk of IgG-mediated HAR/AHXR. Based on the data in this study, we have established a new 2-step screening, which will be used for future clinical kidney xenotransplantation trials.

The highlights of kidney transplantation in2023

In 2023, significant advances were made in various areas of kidney transplantation. Firstly, the use of a balanced crystalloid solution in the recipient appears to prevent the delay in graft function, unlike hypothermia in the donor and normothermic pulsatile perfusion. Understanding the pathophysiology of humoral rejection has progressed, highlighting the major role of HLA class II molecules and innate immune cells (NK and monocytes expressing FCGR3A). An automatic Banff classification algorithm has been developed to better categorize biopsies in currently known diagnoses. CXCL10, combined with other variables, seems effective in ruling out rejection, but its role in routine care is yet to be defined. Regarding cytomegalovirus (CMV), letermovir has been proven effective in preventing CMV disease in D+R- patients, with fewer hematological side effects. For R+ patients, monitoring CMV-specific T-cell immunity is suggested to reduce the duration of antiviral prophylaxis. The only innovation in immunosuppression is imlifidase for highly sensitized patients, guided by French recommendations. A new equation for glomerular filtration rate measurement has been developed for kidney transplant recipients, performing well across various analyzed stratifications. Finally, xenotransplantation is making a comeback this year, generating hope. However, the description of early humoral rejections involving innate immune cells indicates that adjustments are still needed before considering its widespread deployment.

Rejection in the setting of combined Heart and Liver Transplantation

IntroductionEach year the number of combined heart-liver transplants (HLT) increases, with two distinct patient populations proceeding down this pathway. The first are patients with congenital heart disease (CHD), most commonly single ventricle patients palliated with Fontan. The second group are those with long standing congestive hepatopathy, amyloidosis, hemochromatosis, or alcohol induced myopathies and liver disease.One argument for HLT has been the low rate of rejection even among sensitized patients, with reported rejection rates ranging from 0% to 31%. Historically, those with CHD have been highly sensitized which in some cases may prevent or at least delay transplantation. As such, a recent consensus statement by Emamaulee et al. suggest that “there may be an immunological benefit to proceed with HLT with significantly fewer acute cellular and humoral rejection episodes”. The aim of this study is to demonstrate that HLT patients remain at risk for rejection and have required treatment for it. ResultsThere were 15 patients who underwent HLT from January 2017 to February 2022. Of the four patients who did not have CHD, none were considered sensitized, and all underwent induction with basiliximab per our institutional protocol. One of these had rejection. Rejection episodes were identified in four of the 11 CHD patients (36%) patients. ConclusionsIn our study of 15 HLT, including 11 CHD patients (73% denied transplant at ≥ 1 center) demonstrated a higher rate of rejection than previously reported. While theoretically, HLT may mitigate the likelihood of rejection, the risk still exists, and patients benefit from close monitoring commensurate with single organ transplant.

Extracorporeal Photopheresis Reduces Fibrotic and Inflammatory Transcriptomic Biological Marker of Chronic Antibody-mediated Kidney Rejection.

The benefit of extracorporeal photopheresis on the course of kidney transplant rejection is unknown. The aim of our study was to investigate the variations in transcriptomics on graft biopsies when extracorporeal photopheresis was used to treat chronic humoral rejection after kidney transplantation. We retrospectively analyzed the mRNA expression of 770 genes of interest in graft biopsies performed before and after treatment. Eight patients received an average of 23 extracorporeal photopheresis sessions over 4 mo between the 2 biopsies. Transcriptomic analysis of the graft biopsies identified a significant (adjusted P < 0.05) increase in CAV1 mRNA in all patients and a significant decrease in CD19, IL21, PAX5, and SFTPA2 mRNAs in 7 of 8 patients. In patients treated with extracorporeal photopheresis for chronic humoral rejection after renal transplantation, omic analysis of repeated biopsies shows a reduction in fibrotic and inflammatory transcriptomic biologicals markers.

BIOPROSTHETIC VALVE IMPLANTATION AS TYPE OF TRANSPLANTATION: IMMUNOLOGICAL CONSEQUENCES OF NEW CONCEPT

HighlightsImmune processes and mechanisms underlying bioprosthetic heart valve degeneration and rejection of allografts and xenografts are similar.Manufacturers and surgeons can implement effective approaches to prevent immune rejection in the process of production and implantation of prosthetic heart valves in order to delay the process of structural valve degeneration. AbstractBioprosthetic heart valves (BHV) are characterized by low thrombogenicity, thus circumventing the need for long‐term anticoagulation. However, BHV lifespan is limited to 10–15 years because its tissue components are subject to degeneration. Recent research data indicate that immune responses forming the basis of humoral and cellular rejection of allografts and xenografts play a major role in the development of structural valve degeneration (SVD). This review summarizes up-to-date data on immune processes involved in SVD pathogenesis. Moreover, the latest achievements in the development of strategies to reduce the immunogenicity of BHV, such as data on immune compatibility of allogeneic material and the process of deriving low immunogenic biomaterial from genetically modified animals, decellularization of BHV, and the ways of slowing the process of degeneration are analyzed.

Comparative proteomics reveal the humoral immune rejection of pearl oyster Pinctada fucata to xenograft from Pinctada maxima

To investigate the mechanism underlying immune rejection in pearl oyster Pinctada fucata following allograft (P. fucata mantle pieces) and xenograft (P. maxima mantle pieces) transplantations, we analyzed serum samples collected at multiple time points (6, 12, 24, 48, 96, 144, and 192 h) after transplantation using a proteomics approach. We identified 2127 proteins with high confidence according to the selected peptides (false discovery rate = 0.01), among which 1148 exhibited quantitative differences. Functional enrichment analysis revealed significant changes in protein functional categories, including signal transduction, translation, cytoskeleton, and post-translational modifications. Immune-related proteins, such as the ubiquitin-conjugating enzyme E2, apoptosis-linked gene, heat shock protein, and apoptosis inhibitor 5 were associated with allografts and xenografts. Notably, the PI3K-Akt signaling, focal adhesion, and extracellular matrix (ECM)-receptor interaction pathways were enriched among upregulated proteins (xenograft vs. allograft), while the ribosome pathway was enriched among downregulated proteins. These findings suggest that implantation stress may affect protein biosynthesis or activate multiple molecular pathways involved in key immune proteins. Furthermore, the xenograft group demonstrated greater sensitivity in recognizing and responding to foreign substances compared to the allograft group. This heightened responsiveness enabled the xenograft group to rapidly activate humoral immune factors, which triggered the signaling pathway responsible for suppressing the inflammatory response. This study provides novel insights into the immune reactions of host oysters to grafted mantle pieces, particularly xenografts, and may offer strategies to improve xenograft transplantation technologies in the pearl culture industry.

Difficulties in diagnosing and predicting possible complications in patients after heart transplantation: single-center experience in the Krasnodar region

Aim. To evaluate the early and long-term outcomes of heart transplantation (HT) at the Research Institute of the S. V. Ochapovsky Regional Clinical Hospital № 1.Material and methods. On the basis of the Research Institute of the S. V. Ochapovsky Regional Clinical Hospital № 1 from March 2010 to March 2023, 230 HTs were carried out. Among the patients, men predominated 86% (n=198), women — 14% (n=32). The mean age was 48,3±11,7 years. The reason for HT in 42,6% (n=98) was ischemic cardiomyopathy (ICM), in 40% (n=92) — dilated cardiomyopathy (DCM), while 17,4% were operated on for another cardiac pathology (n=40). All recipients underwent immunological examination, endomyocardial biopsy (EMB), 2D-speckle-tracking echocardiography (2D-STE), transthoracic echocardiography (TTE), coronary angiography (CAG), as well as a number of studies for early diagnosis of possible cancer complications.Results. Acute rejection during the first three years was detected in 77 recipients (42,5%), of which cellular rejection (grade ≥2, 3) and humoral rejection was verified in 49 and 28 recipients, respectively. During the entire follow-up period, de novo anti-human leukocyte antigen (HLA) antibodies were detected in 34 recipients in the posttransplantation period, of which 50% (n=17) and 35% (n=12) were diagnosed with humoral and cellular rejection, respectively. Of the 34 patients with anti-HLA antibodies, 11 (32%) died. All of them died due to a humoral rejection. The survival rate of patients with antibodies was lower (59%) than in patients without antibodies (66%), p=0,023. The annual survival rate of all patients after transplantation in our center was 83,1% (during the first year after transplantation, 30 and 9 patients died due to an acute rejection and infectious complications, respectively).Conclusion. Since the introduction and modification of immunosuppressive therapy regimens, tremendous progress has occurred, and the incidence of acute cellular rejection has decreased. However, the risk of humoral rejection and long-term complications remains one of the main reasons for graft failure.

Impact of imlifidase treatment on immunoglobulins in an HLA-hypersensitized lupus nephritis patient with anti-SSA/SSB antibodies after kidney transplantation: A case report

Bacterial recombinant cysteine protease Ides (imlifidase, Idefirix®, Hansa Biopharma) is used to prevent humoral transplant rejection in highly HLA-sensitized recipients, and to control IgG-mediated autoimmune diseases. We report the case of a 51 years old woman suffering from lupus nephritis with end stage kidney disease, grafted for the second time and pre-treated with imlifidase. The patient was HLA-hypersensitized (calculated Panel Reactive Antibodies [Abs], cPRA>99 %) and has three preformed Donor Specific Antibodies (DSA). Circulating immunoglobulins were monitored at initiation (0, 6, 36, 72 and 96 h), and at Ab recovery one and two months following imlifidase injection. From baseline, the higher depletion was reported after 36h for total IgG (−75 %) and IgG subclasses (−87 % for IgG1, IgG2 and IgG3, -78 % for IgG4), while no significant impact on IgA and IgM was observed. Anti-SSA 60 kDa and anti-SSB auto-Abs quickly decreased after imlifidase injection (−96 % for both after 36 h) as well as post-vaccinal specific IgG (−95 % for tetanus toxoid, −97 % for pneumococcus and −91 % for Haemophilus influenzae Abs after 36 h). At the Ab recovery phase, total IgG and anti-SSA60/SSB Abs reached their initial level at two months. Regarding alloreactive Abs, anti-HLA Abs including the three DSA showed a dramatic decrease after injection with 100 % depletion from baseline after 36 h as assessed by multiplex single bead antigen assay, leading to negative crossmatches using both lymphocytotoxicity (LCT) and flow cell techniques. DSA rebound at recovery was absent and remained under the positivity threshold (MFI = 1000) after 6 months. The findings from this case report are that imlifidase exerts an early depleting effect on all circulating IgG, while IgG recovery may depend in part from imlifidase's capacity to target memory B cells.