Development Of Donor-specific Antibodies Research Articles

Association between Respiratory Virus Infection and Development of De Novo Donor-Specific Antibody in Lung Transplant Recipients.

Chronic lung allograft dysfunction (CLAD) is the most common cause of long-term lung allograft failure. Several factors, including respiratory virus infection (RVI), have been associated with CLAD development, but the underlying mechanisms of these associations are not well understood. We hypothesize that RVI in lung transplant recipients elicits the development of donor-specific antibodies (DSAs), thus providing a mechanistic link between RVI and CLAD development. To test this hypothesis, we retrospectively evaluated for the presence of HLA antibodies in a cohort of lung transplant recipients with symptomatic RVI within the first four months post-transplant using sera at two time points (at/directly after the transplant and following RVI) and time-matched controls without RVI (post-transplant). We found a trend toward the development of de novo DSAs in those with symptomatic RVI versus controls [6/21 (29%) vs. 1/21 (5%), respectively, p = 0.09]. No cases or controls had DSA at baseline. We also found increased rates of CLAD and death among those who developed class II DSA versus those who did not (CLAD: 5/7 (71.4%) vs. 19/34 (54.3%), death: 5/7 (71.4%) vs. 17/35 (48.6%)). Prospective studies evaluating the temporal development of DSA after RVI in lung transplant patients and the subsequent outcomes are warranted.

Optimization of Hypercholesterolemia Treatment after Heart Transplant: The Role of PCSK9 Inhibitors.

Previous studies have reported the benefit of statins after heart transplant (HT). However, the use of high-dose statins might be limited in some HT patients due to intolerance and interactions with immunosuppression or might not be enough to achieve low-density lipoprotein (LDL) cholesterol goals. Hyperlipidemia has been associated with coronary allograft vasculopathy. Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors might be a safe and effective option in HT patients with suboptimal lipid control. In a retrospective study, we identified HT patients in our center with LDL cholesterol >100 mg/dL, after diet modifications and up-titration of statins to maximum tolerated dose, treated with PCSK9i. The primary endpoint was LDL reduction one month after, and secondary endpoints were the development of donorspecific HLA antibodies (DSA) and the presence of coronary allograft vasculopathy or rejection. From January, 2018, to January, 2024, we identified five HT patients treated with PCSK9 inhibitors. In all cases, evolocumab was used. A significant reduction in LDL cholesterol was observed (151.6 ± 13.5 mg/dl to 72.4 ± 14.6 mg/dl; p = 0.04, mean reduction 75.7 ± 14.1 mg/dl), as well as in total cholesterol (231 ± 34.6 mg/dl to 152.2 ± 38.9 mg/dl; p < 0.01, mean reduction 78.8 ± 22.2 mg/dl). A significant increase in HDL cholesterol was not observed (45.4 ± 10.9 mg/dl to 46.2 ± 11.1 mg/dl; p = 0.60). One patient developed DSA five years after treatment onset. Rejection and coronary allograft vasculopathy were not observed. PCSK9 inhibitors are safe and effective in reducing LDL in HT patients. However, larger studies are needed to clarify if they can reduce the development of coronary allograft vasculopathy.

HLA-DQ heterodimer mismatch number is associated with de novo donor-specific antibody development in pediatric kidney transplant recipients

HLA-DQ heterodimer mismatch number is associated with de novo donor-specific antibody development in pediatric kidney transplant recipients

HLA-DR/DQ eplet mismatch predicts risk of de novo donor-specific antibody development in a multi-ethnic Southeast Asian cohort of kidney transplant recipients

HLA-DR/DQ eplet mismatch predicts risk of de novo donor-specific antibody development in a multi-ethnic Southeast Asian cohort of kidney transplant recipients

Marginal zone B cells are required for optimal humoral responses to allograft

Antibody-mediated rejection (AMR) is among the leading causes of graft failure in solid organ transplantation. However, AMR treatment options are limited by an incomplete understanding of the mechanisms underlying de novo donor-specific antibody (DSA) generation. The development of pathogenic isotype-switched DSA in response to transplanted allografts is typically attributed to follicular B cells undergoing germinal center reaction whereas the contribution of other B cell subsets has not been previously addressed. The current study investigated the role of recipient marginal zone B cells (MZ B cells) in DSA responses using mouse models of heart and renal allotransplantation. MZ B cells rapidly differentiate into antibody-secreting cells in response to allotransplantation. Despite the selective depletion of follicular B cells in heart allograft recipients, MZ B cells are sufficient for T-dependent IgM and early IgG DSA production. Furthermore, the presence of intact MZ B cell subset is required to support the generation of pathogenic isotype-switched DSA in renal allograft recipients containing donor-reactive memory helper T cells. These findings are the first demonstration of the role of MZ B cells in humoral alloimmune responses following solid organ transplantation and identify MZ B cells as a potential therapeutic target for minimizing de novo DSA production and AMR in transplant recipients.

HLA-DR/DQ eplet mismatch predicts de novo donor-specific antibody development in multi-ethnic Southeast Asian kidney transplant recipients on different immunosuppression regimens.

Eplet mismatch has been recognized as a more precise strategy for determining HLA compatibility by analyzing donor-recipient HLA differences at the molecular level. However, predicting post-transplant alloimmunity using single-molecule eplet mismatch categories has not been validated in Asian cohorts. We examined a cohort of Southeast Asian kidney transplant recipients (n = 234) to evaluate HLA-DR/DQ eplet mismatch as a predictor of de novo donor-specific antibody (dnDSA) development. HLA-DR/DQ single-molecule eplet mismatch was quantified using HLA Matchmaker, and we utilized previously published HLA-DR/DQ eplet mismatch thresholds to categorize recipients into alloimmune risk groups and evaluate their association with dnDSA development. Recognizing that the predominance of cyclosporine use (71%) may alter published eplet mismatch thresholds derived from a largely tacrolimus-based (87%) cohort, we evaluated cohort-specific thresholds for HLA-DR/DQ single-molecule eplet mismatch categories. Recipient ethnicities included Chinese (65%), Malays (17%), Indians (14%), and others (4%). HLA-DR/DQ dnDSA developed in 29/234 (12%) recipients after a median follow-up of 5.4 years, including against isolated HLA-DR (n = 7), isolated HLA-DQ (n = 11), or both (n = 11). HLA-DR/DQ single-molecule eplet mismatch risk categories correlated with dnDSA-free survival (p = 0.001) with low-risk recipients having a dnDSA prevalence of 1% over 5years. The cohort-specific alloimmune risk categories improved correlation with HLA-DR/DQ dnDSA-free survival and remained significant after adjusting for calcineurin inhibitor and anti-metabolite immunosuppression (p < 0.001). We validated the performance of single-molecule eplet mismatch categories as a prognostic biomarker for HLA-DR/DQ dnDSA development in a cohort of predominantly Asian kidney transplant recipients after adjusting for different immunosuppression regimens.

Activation and Regulation of Indirect Alloresponses in Transplanted Patients With Donor Specific Antibodies and Chronic Rejection.

Following transplantation, human CD4+T cells can respond to alloantigen using three distinct pathways. Direct and semi-direct responses are considered potent, but brief, so contribute mostly to acute rejection. Indirect responses are persistent and prolonged, involve B cells as critical antigen presenting cells, and are an absolute requirement for development of donor specific antibody, so more often mediate chronic rejection. Novel in vitro techniques have furthered our understanding by mimicking in vivo germinal centre processes, including B cell antigen presentation to CD4+ T cells and effector cytokine responses following challenge with donor specific peptides. In this review we outline recent data detailing the contribution of CD4+ T follicular helper cells and antigen presenting B cells to donor specific antibody formation and antibody mediated rejection. Furthermore, multi-parametric flow cytometry analyses have revealed specific endogenous regulatory T and B subsets each capable of suppressing distinct aspects of the indirect response, including CD4+ T cell cytokine production, B cell maturation into plasmablasts and antibody production, and germinal centre maturation. These data underpin novel opportunities to control these aberrant processes either by targeting molecules critical to indirect alloresponses or potentiating suppression via exogenous regulatory cell therapy.

Unique Lessons From the Natural Progression of Rejection in Human Uterine Allografts.

Uterus transplantation (UTx) is a novel treatment for absolute uterine infertility. Acute T cell-mediated rejection (TCMR) can be monitored only through serial cervical biopsies. This study, the first of its kind in human transplantation, evaluated clinical, serological, and pathophysiological manifestations of allograft rejection from immunosuppression withdrawal (ISW) to graft hysterectomy (Hx). Following live birth, immunosuppression was abruptly withdrawn from six living-donor UTx recipients. ISW occurred at a median of 7.4 weeks before graft Hx. Post-ISW signs of rejection included: (1) discoloration of the cervix; (2) increased uterine size compared to day of ISW; (3) serological evidence of eosinophilia and progressive development of donor-specific antibodies (DSA) or child-specific antibodies (CSA); (4) histopathological evidence of TCMR in cervical biopsies preceding the development of antibodies in serum; and (5) C4d deposition in tissue before formation of DSA or CSA in all but two recipients. At graft Hx, endometrial glands were preferentially targeted for destruction over stroma while parametrial arteries displayed variable arteritis and fibrointimal hyperplasia. Recognition of the progression of uterine allograft rejection may be important for other human organ recipients and drive research on modulation of immunosuppression and the paradoxical relationship between adaptive cellular and humoral immunity in natural pregnancies. ClinicalTrials.gov identifier: NCT02656550.

Allogeneic HLA Humoral Immunogenicity and the Prediction of Donor-Specific HLA Antibody Development.

The development of de novo donor-specific HLA antibodies (dnDSAs) following solid organ transplantation is considered a major risk factor for poor long-term allograft outcomes. The prediction of dnDSA development is a boon to transplant recipients, yet the assessment of allo-HLA immunogenicity remains imprecise. Despite the recent technological advances, a comprehensive evaluation of allo-HLA immunogenicity, which includes both B and T cell allorecognition, is still warranted. Recent studies have proposed using mismatched HLA epitopes (antibody and T cell) as a prognostic biomarker for humoral alloimmunity. However, the identification of immunogenic HLA mismatches has not progressed despite significant improvements in the identification of permissible mismatches. Certainly, the prediction of dnDSA development may benefit permissible HLA mismatched organ transplantations, personalized immunosuppression, and clinical trial design. However, characteristics that go beyond the listing of mismatched HLA antibody epitopes and T cell epitopes, such as the generation of HLA T cell epitope repertoires, recipient's HLA class II phenotype, and immunosuppressive regiments, are required for the precise assessment of allo-HLA immunogenicity.

Induction immunosuppression strategies and outcomes post-lung transplant: A single center experience

PurposeCurrently 80% of lung transplant centers use induction immunosuppression. However, there is a lack of standardization of induction protocols within and across lung transplant centers. This study explores the association of two different induction immunosuppression strategies used at our center [single dose rabbit antithymocyte globulin (rATG) vs. alemtuzumab] compared to no induction with immunologic and clinical outcomes after lung transplantation. MethodsA total of 174 consecutive lung transplant recipients (LTR) between 2016 and 2019 were included in the analysis. Twenty nine LTR (16.7%) received no induction, 22 LTR (12.6%) received alemtuzumab, 123 LTR (70.6%) received a single dose of rATG; 1.5 mg/kg within 24 h of transplant for induction. All LTR had a negative flow cytometry crossmatch on the day of the transplant. All LTR were assessed for de novo HLA donor-specific antibodies (DSA) development and clinical outcomes, including the risk of acute cellular rejection (ACR), antibody-mediated rejection (AMR), chronic lung allograft dysfunction (CLAD), and overall survival post-transplant. ResultsThe median lung allocation score (LAS) was significantly higher in LTR that did not receive Induction immunosuppression (76; range = 35.3–94.3) compared to induction with rATG (41.6; range = 31.6–91) and alemtuzumab (51; range = 33.1–88.2) (p < 0.001). De novo HLA DSA were detected in 50/174 (28.7%) LTR within 12 months post-transplant. They were detected in 13/29 (44.8%) LTR without induction immunosuppression compared to 28/123 (22.8%) and 9/22 (40.9%) LTR with rATG and alemtuzumab induction, respectively (p = 0.02). The percent freedom from ACR rates between LTR who received alemtuzumab induction was significantly higher compared to LTR who received rATG or no induction at 1 (p = 0.02), 2 (p = 0.01) and 3 (p = 0.05) years post-transplant. In addition, the overall 1-year survival rates were significantly higher in LTR who received rATG or alemtuzumab induction compared to LTR without induction immunosuppression (p = 0.02). ConclusionInduction immunosuppression strategies utilizing rATG or Alemtuzumab have unique and contrasting benefits in LTR. Combination of alemtuzumab induction and a lower dose of maintenance immunosuppression may reduce the incidence of ACR in LTR. Single-dose rATG or alemtuzumab induction immunosuppression may also improve the 1 year overall LTR survival compared to no induction.

Pseudomonas aeruginosa infection correlates with high MFI donor-specific antibody development following lung transplantation with consequential graft loss and shortened CLAD-free survival

BackgroundDonor-specific antibodies (DSAs) are common following lung transplantation (LuTx), yet their role in graft damage is inconclusive. Mean fluorescent intensity (MFI) is the main read-out of DSA diagnostics; however its value is often disregarded when analyzing unwanted post-transplant outcomes such as graft loss or chronic lung allograft dysfunction (CLAD). Here we aim to evaluate an MFI stratification method in these outcomes.MethodsA cohort of 87 LuTx recipients has been analyzed, in which a cutoff of 8000 MFI has been determined for high MFI based on clinically relevant data. Accordingly, recipients were divided into DSA-negative, DSA-low and DSA-high subgroups. Both graft survival and CLAD-free survival were evaluated. Among factors that may contribute to DSA development we analyzed Pseudomonas aeruginosa (P. aeruginosa) infection in bronchoalveolar lavage (BAL) specimens.ResultsHigh MFI DSAs contributed to clinical antibody-mediated rejection (AMR) and were associated with significantly worse graft (HR: 5.77, p < 0.0001) and CLAD-free survival (HR: 6.47, p = 0.019) compared to low or negative MFI DSA levels. Analysis of BAL specimens revealed a strong correlation between DSA status, P. aeruginosa infection and BAL neutrophilia. DSA-high status and clinical AMR were both independent prognosticators for decreased graft and CLAD-free survival in our multivariate Cox-regression models, whereas BAL neutrophilia was associated with worse graft survival.ConclusionsP. aeruginosa infection rates are elevated in recipients with a strong DSA response. Our results indicate that the simultaneous interpretation of MFI values and BAL neutrophilia is a feasible approach for risk evaluation and may help clinicians when to initiate DSA desensitization therapy, as early intervention could improve prognosis.

Development of donor specific antibodies after SARS-CoV-2 vaccination: What do we know so far?

Development of donor specific antibodies after SARS-CoV-2 vaccination: What do we know so far?

Long-Term Outcome Following Treatment With Allogeneic Mesenchymal Stem/Stromal Cells for Radiation-Induced Hyposalivation and Xerostomia.

Adipose-derived mesenchymal stem/stromal cells (ASCs) are proposed as a new xerostomia treatment. The study evaluated the long-term safety and effectiveness of allogeneic ASCs in radiation-induced xerostomia among patients with previous oropharyngeal cancer. This study constitutes 3-year follow-up on the original 10 patients who received allogeneic ASCs injections to the submandibular and parotid glands as part of the MESRIX-II trial. The MESRIX-II trial included the preliminary 4-month follow-up. The primary endpoint was long-term safety. Secondary endpoints were effectiveness evaluated by changes in salivary flow rate and patient-reported outcomes (PROs). Immune response was evaluated by assessing the development of donor-specific antibodies (DSA). All 10 MESRIX-II patients completed the long-term follow-up (ie, no missing data). During the long-term follow-up, 2 patients encountered a significant adverse event, which was determined to be unrelated to the treatment. No DSAs were detectable at 3 years. The stimulated salivary flow rate increased significantly from an average of 0.66 mL/minute at baseline to 0.86 mL/minute at follow-up, corresponding to an increase of 0.20 [95% CI 0.08 to 0.30] mL/minute, or approximately 30%. Among the PROs, sticky saliva symptoms were reduced, with a -20.0 [95% CI -37.3 to -2.7] units. In conclusion, this study is the first to present long-term follow-up outcomes of allogeneic ASC treatment as a therapeutic option for radiation-induced xerostomia. The study found that ASC treatment appears safe, and there were no indications of adverse immune responses at the 3-year follow-up. Further studies are warranted to evaluate the findings in larger settings.

#3036 The influence of first renal graft on second graft rejection and survival: the importance of revisiting histocompatibility and clinical outcomes

Abstract Background and Aims Kidney retransplantation confers a robust survival benefit over dialysis and recent data has shown similar outcomes to first kidney transplant. The number of HLA mismatches is an important predictor of graft loss and sensitization and the presence of donor specific antibodies (DSA) -pre and -post transplant is a major risk factor for rejection and worst outcomes. However, the importance of HLA matching of first graft and the relevance of first donor DSAs on second graft outcomes is less known. Our aim was to identify risk factors to second graft acute rejection and graft loss, related to second and first graft features. Method We performed a retrospective, longitudinal study including all patients submitted to a 2nd kidney transplant between January 2008 and December 2021, excluding patients with more than 2 grafts or multi-organ transplant. Clinical and histocompatibility data from the first and second donor and recipient were collected. HLA antibodies were detected by solid phase assays and considered if MFI &amp;gt;2500. For subsequent kidney transplants, repeated mismatches are not allowed and unacceptable antigens are those for which the patient has pre-formed -A, -B and -DR antibodies, with MFI&amp;gt;1000. Biopsy proven acute rejection was defined according to Banff 2017 criteria. Follow-up was 31st December 2023 for functioning grafts or time to graft failure, with a mean time of 92 ± 53 months. Results We included 114 patients, 73 (64%) males, mostly Caucasians (96%), with a mean age of 43.9 ± 13 years at 2nd transplant. First kidney transplant was performed before 2010 for 99 patients (87%), with a median first graft survival of 82.5 [12.5-144] months and 19 patients (16.7%) presented primary disfunction due to surgical/vascular complications. After graft loss, 43 patients (37.7%) had their graft removed. For second transplant, 11 (9.6%) patients had a living donor. Induction therapy with thymoglobulin occurred in 94 patients (83%) and maintenance therapy with mycophenolic acid, calcineurin inhibitors and steroids was prescribed in 83 patients (73%). During follow-up, 20 patients (17.5%) presented biopsy proven acute rejection, 13 (65%) T cell mediated and 7 (35%) antibody-mediated, the majority during the first-year post-transplant (N = 17, 85%). The risk factors for second graft rejection are summarized in Table 1. Patients with a first graft nephrectomy had a higher risk of acute rejection (OR 3.9, 95% CI [1.4-10.9], p &amp;lt; 0.006) and were more susceptible to the development of second donor post-transplant DSA (58% vs 35%, p = 0.02). Death censored second allograft loss occurred in 24 patients (21%) at follow up and acute rejection was an important risk factors (OR 4.3, 95% CI [1.5-12.1], p = 0.004). First-year graft survival was 93% and a survival at follow up was 79%. On survival analysis the presence of second graft DSA was a major risk factor for graft loss, especially class 2 -DQ and -DR. First transplant total mismatch load, especially on class 1 contributed to worst graft survival. Conclusion Worst outcomes in first kidney transplant were related with an increased risk of acute rejection in second graft and 1st graft nephrectomy increases the risk of the development of 2nd graft DSA and acute rejection. First transplant mismatch load decreased second graft survival.

Clinical conundrums in pediatric kidney transplantation: What we know about the role of angiotensin II type I receptor antibodies in pediatric kidney transplantation and the path forward.

Antibodies to angiotensin II type 1 receptor (AT1R-Abs) are among the most well-studied non-HLA antibodies in renal transplantation. These antibodies have been shown to be common in pediatric kidney transplantation and associated with antibody-mediated rejection (AMR), vascular inflammation, development of human leukocyte donor-specific antibodies (HLA DSA), and allograft loss. As AT1R-Ab testing becomes more readily accessible, evidence to guide clinical practice for testing and treating AT1R-Ab positivity in pediatric kidney transplant recipients remains limited. This review discusses the clinical complexities of evaluating AT1R-Abs given the current available evidence.

Long-term outcomes of two-dose alemtuzumab induction in pediatric kidney transplantation.

Alemtuzumab is a lymphocyte depleting agent used for induction in kidney transplant, but long-term information on its use in pediatric recipients remains sparse. We performed a single-center retrospective cohort study of 57 pediatric kidney transplant recipients receiving alemtuzumab 20 mg/m2/dose ×2 doses for induction immunosuppression. All patients underwent surveillance biopsies, and 91.3% underwent steroid withdrawal by day 4 post-transplant. Outcomes of interest included graft survival, development of donor specific antibodies (DSA), incidence of viremia and PTLD, and duration of lymphopenia. Median follow-up time was 7.9 years (IQR 5-13.6 years). Median graft survival was 16.5 years (95% CI 11.6-unknown). DSA developed in 36.5% at a median of 944 days (IQR 252-2113 days). Incidences of BK polyomavirus DNAemia (BKPyV-DNAemia), CMV DNAemia, and EBV DNAemia were 38.6%, 22.8%, and 14%, respectively; one patient developed PTLD at 13.3 years post-transplant. Median duration of lymphopenia was 365 days (IQR 168-713 days); 19.3% of patients remained lymphopenic at 3 years post-transplant. There was no association between duration of lymphopenia and graft survival, rejection, DSA detection, or viremia. A two-dose alemtuzumab induction protocol can have excellent outcomes with a steroid-free maintenance immunosuppression regimen. More comprehensive, multicenter, comparative studies of pediatric kidney transplant are needed to improve long-term outcomes.

(447) - The ABCs of DSAs: Incidence, Class, Gene and Strength of Donor Specific Antibody Development in the First Year After Heart Transplant

(447) - The ABCs of DSAs: Incidence, Class, Gene and Strength of Donor Specific Antibody Development in the First Year After Heart Transplant

(1424) - Clinical Implications of Early vs Late Development of Donor-Specific Antibodies After Lung Transplant

(1424) - Clinical Implications of Early vs Late Development of Donor-Specific Antibodies After Lung Transplant

Anti-intercellular adhesion molecule 1 monomaintenance therapy induced long-term liver allograft survival without chronic rejection

Calcineurin inhibitors (CNIs) are essential in liver transplantation (LT); however, their long-term use leads to various adverse effects. The anti–intercellular adhesion molecule (ICAM)-1 monoclonal antibody MD3 is a potential alternative to CNI. Despite its promising results with short-term therapy, overcoming the challenge of chronic rejection remains important. Thus, we aimed to investigate the outcomes of long-term MD3 therapy with monthly MD3 monomaintenance in nonhuman primate LT models. Rhesus macaques underwent major histocompatibility complex–mismatched allogeneic LT. The conventional immunosuppression group (Con-IS, n = 4) received steroid, tacrolimus, and sirolimus by 4 months posttransplantation. The induction MD3 group (IN-MD3, n = 5) received short-term MD3 therapy for 3 months with Con-IS. The maintenance MD3 group (MA-MD3, n = 4) received MD3 for 3 months, monthly doses by 2 years, and then quarterly. The MA-MD3 group exhibited stable liver function without overt infection and had significantly better liver allograft survival than the IN-MD3 group. Development of donor-specific antibody and chronic rejection were suppressed in the MA-MD3 group but not in the IN-MD3 group. Donor-specific T cell responses were attenuated in the MA-MD3 group. In conclusion, MD3 monomaintenance therapy without maintenance CNI provides long-term liver allograft survival by suppressing chronic rejection, offering a potential breakthrough for future human trials.

Including the liver in the visceral allograft: Impact on donor-specific anti-HLA antibodies and long-term outcomes

Humoral immunity emerges as a risk factor for graft failure after visceral transplantation (VTx) and development of donor-specific anti-HLA antibodies (DSAs) has been linked with poor outcomes. In most cases, a simultaneous liver transplant can be safely performed in sensitized patients with DSA and appears protective against lymphocytotoxic antibodies. We investigated the incidence of acute (AR) and chronic rejection (CR) in 32 VTx without any B cell-depleting pre-treatment (6 isolated intestinal transplants (IT) and 26 liver-containing, multivisceral transplants (MVT) and assessed the presence of donor-specific antibodies (DSA) pre- and post-transplantation. Twenty-one patients (65 %) developed AR, 15 (57 %) of the MVT and 6 (100 %) of the IT (p = 0.05). CR occurred in 4 IT (60 %, p < 0.001). At one month, de novo DSA were present in 71 % of VTx (66 % MVT vs 100 % IT, p = 0.09). At the last available follow-up, 69 % of the MVT and 50 % of the IT patients were DSA-free. De novo DSA seemed more persistent (7/19, 37 %) than pre-Tx DSA (1/6, 17 %; p = n.s.), de novo DSA were more frequently specific for HLA class II than class I, 16/19 (84 %) vs. 7/19 (37 %; p = 0.003), and HLA-DQ was their most frequent target HLA. DQ mismatches appeared to be a risk factor for developing de novo DSA. In conclusion, liver-containing visceral allografts have superior short- and long-term outcomes compared with liver-free allografts. De novo DSA develop early and frequently after VTx performed without B cell-depleting induction therapy, but the exact role of DSA in the pathogenesis of rejection remains unclear.