Donor-specific Antibodies Group Research Articles

Impact of Preformed Donor-specific Antibodies in Comparison to ABO Incompatibility in Living Donor Liver Transplantation: A Propensity Score-Matched Analysis.

Immunological factors play a pivotal role in the outcomes of solid organ transplantation. We aimed to elucidate the effects of donor-specific antibodies (DSAs) and ABO compatibility on living donor liver transplantation (LDLT) outcomes. A retrospective analysis was conducted on 584 LDLT recipients from 2015 to 2020. The recipients were stratified into 3 groups: ABO-compatible recipients without DSAs (group 1), ABO-compatible recipients with DSAs (group 2), and ABO-incompatible recipients without DSAs (group 3). Propensity score matching was used for balanced comparisons. In the matched comparisons, group 2 exhibited a higher incidence of T cell-mediated rejection compared with group 1 (22.7% versus 4.5%, P = 0.030). Despite this, the 5-y survival rates were similar between groups 1 and 2 (81.6% versus 95.5%, P = 0.085). Group 3, in comparison with group 1, showed elevated rates of cytomegalovirus infection (23.2% versus 7.3%, P = 0.008), T cell-mediated rejection (28.0% versus 7.3%, P = 0.001), and antibody-mediated rejection (13.4% versus 0%, P = 0.001). However, the survival rates were comparable between group 3 and group 1 (82.0% versus 86.5%, P = 0.220, respectively). Comparisons between group 2 and group 3 did not reveal significant differences in postoperative outcomes or survival rates ( P > 0.05). DSA positivity and ABO incompatibility contribute to distinct posttransplant complications in LDLT. The integrated consideration of both factors in pretransplant assessment may enhance risk stratification and inform tailored interventions. Further research is required to corroborate these findings and provide mechanistic insights.

Evaluation of serial monitoring of donor-specific antibodies in pediatric and adult intestinal/multivisceral transplant recipients.

The study purpose was to add to limited literature assessing anti-HLA donor-specific antibody (DSA) appearance, clearance, specificity, and impact in intestinal/multivisceral (MV) transplant as well as the value of serial monitoring following an institutional protocol shift implementing serial monitoring. This single-center retrospective review included intestinal/MV recipients transplanted 1/1/15-9/31/17 with completed DSA testing. Patients were divided into groups based on DSA presence post-transplant. The primary outcome was biopsy-proven acute rejection (BPAR). Secondary outcomes included graft loss and death. Descriptive analysis of DSA was completed. Of the 35 intestinal/MV recipients (60% pediatric) with DSA testing, 24 patients had post-transplant DSA. Fifteen patients in the DSA(+) group had T-cell-mediated BPAR versus five in the DSA(-) group (63% vs 45%, p = .47). Days to BPAR were 25 [IQR 19-165] (DSA(+) group) versus 232 [IQR 25.5-632.5] (DSA(-) group) (p = .066). There were no differences between groups for graft loss or death. One hundred and five DSA were identified in the DSA(+) group with 63% being class II, and 54% cleared during follow-up. DSA were directed against 50 different HLA alleles, with the most common being directed against HLA- DQ (35%). Time to first DSA and to clearance did not differ between class I and II. Findings confirm previous data that suggest post-transplant DSA in this population may lead to increased BPAR or shorter time to BPAR, although not statistically significant. Most DSA were identified within the first month after transplant, and ahead of rejection identification on biopsy. DSA therefore may have utility as an early rejection biomarker and use may be considered in place of early protocol biopsies, particularly in pediatric patients. We identified novel findings of DSA directed against a large breadth of HLA in intestinal/MV patients.

Impact of pre-transplant donor specific antibodies detected by Luminex with negative microlymphocytotoxicity assay and flow crossmatch in live-related renal transplant recipients.

The Luminex assay, where beads are coated with a single HLA antigen, has been shown to detect HLA antibodies with more sensitivity and specificity as compared to microlymphocytotoxicity (CDC) assay and flow cross match (FCXM). We report the impact of low Mean Flourescence intensity (MFI) pre-transplant DSA by Luminex with negative CDC and FCXM on acute rejection, graft function, and survival. In this retrospective study between January 2015 to December 2021, 45 recipients had pre-transplant anti-HLA donor-specific antibodies (DSAs) detected by Luminex. Two control groups of 45 patients each matched for age and gender, first with non-DSA HLA antibodies and second with no antibodies by Luminex were selected to compare outcomes with DSA group. In the DSA group of 45, 22 (48.8%) had class I (MFI mean 4043±1909, range: 1096-7111), 20 (44.4%) class II (MFI mean 3601±2310, range: 1031-9259), and 3 (6.6%) both class I (MFI mean 4746±1922) and class II (MFI mean 3940±2312) antibodies. Acute rejection episodes were reported in 15.6%, DSA group, 17.8% in non-DSA, and 24.4% in no antibody group (p=.538). Death censored graft survival at 1 and 5 years was 98% and 93% in DSA group, 100% and 95% in non-DSA and 93% and 85% in the no antibody group (p=.254). Patients with low MFI DSA pre-transplant, with a negative CDC and FCXM under ATG induction, have similar graft outcomes at 1 and 5 years when compared to non-DSA and no antibody groups.

Serum Soluble B Cell-Activating Factor Is a Non-Invasive Biomarker of Antibody-Mediated Rejection in Kidney Allograft With Satisfactory Risk Stratification Performance But Negligible Diagnostic Value.

ObjectivesB cell-activating factor (BAFF), which is critical in the activation and differentiation of B cells, is a candidate diagnostic and predictive biomarker for antibody-mediated rejection (ABMR). We aimed to investigate the value of serum soluble BAFF (sBAFF) for the diagnosis and risk stratification of ABMR after kidney transplantation.MethodsIn the diagnostic study, sBAFF level among ABMR (n = 25), T cell-mediated rejection (TCMR) (n = 14), 4 other pathological lesions (n = 21), and stable allograft function group (n = 15) were compared. In the nested case-control study, kidney allograft recipients with de novo donor-specific antibody (DSA) or ABMR (n = 16) vs. stable allograft function (n = 7) were enrolled, and sBAFF was measured preoperatively, at D7, M1, M3, M6, M9, M12, M18 posttransplant and at allograft biopsy.ResultsThere was no significant difference in sBAFF level at biopsy between ABMR and non-ABMR groups. Longitudinal study showed that the sBAFF levels decreased dramatically at D7 in both groups. The sBAFF level in the DSA group started to increase within M1, while in the stable group, it maintained a low level until M3 and M6. The sBAFF levels of the DSA group were significantly higher than that of the stable group at M1 [1,013.23 (633.97, 1,277.38) pg/ml vs. 462.69 (438.77, 586.48) pg/ml, P = 0.005], M3 [1,472.07 (912.79, 1,922.08) pg/ml vs. 561.63 (489.77, 630.00) pg/ml, P = 0.002], and M6 [1,217.95 (965.25, 1,321.43) pg/ml vs. 726.93 (604.77, 924.60) pg/ml, P = 0.027]. sBAFF levels at M3 had the best predictive value for the DSA/ABMR with the area under the receiver operating characteristic (AUROC) curve value of 0.908. The predictive performance of the maximum (max) change rate from D7 to the peak within M3 was also excellent (AUROC 0.949, P = 0.580).ConclusionWe clarified by a diagnostic study that sBAFF is not a diagnostic biomarker for ABMR in kidney transplantation and revealed by a nested case-control study that sBAFF values at M3 posttransplant and dynamic changes in sBAFF within M3 posttransplant have a good predictive value for the DSA/ABMR. It provides a useful tool for early screening of low-risk patients with negative preoperative DSA for the risk of developing postoperative DSA in kidney allograft recipients.

Anti-HLA DQ Antibodies Are Associated with Chronic Lung Allograft Dysfunction in a Pediatric Lung Transplant Population

<h3>Purpose</h3> Chronic lung allograft dysfunction (CLAD) limits long term survival after lung transplantation. Antibody mediated rejection (AMR) has been associated with earlier CLAD development, but studies are limited in children. Clinical AMR can exist on a spectrum from subclinical to definite AMR based on the presence of anti-HLA donor specific antibodies (DSA), allograft dysfunction, and histopathologic findings, with DSA development first to appear. This study aims to describe the relationship of elevated DSA with clinical outcomes in a single center pediatric lung transplant population. <h3>Methods</h3> This was a single center, retrospective study. Pediatric bilateral lung transplant recipients were included from 2002-2020 if they had longitudinal HLA and lung function data for at least 6 months after transplantation. Preliminary analyses with chi-squared or Fisher's exact test for categorical variables and ANOVA or Kruskal-Wallis for continuous variables were used. DSA were detected with single-antigen bead arrays, and elevated DSA was defined as a mean fluorescence intensity level above 500. <h3>Results</h3> 34 patients were included: 19 with elevated DSA and 15 without. Most patients had subclinical AMR (n=10) without allograft dysfunction and two patients had definite AMR, based on the 2018 Banff consensus statement. The proportion of patients who developed CLAD was significantly higher in the elevated DSA group and had an earlier onset of CLAD. Average graft longevity and rates of acute cellular rejection, while not significant, trended towards shorter survival and higher rates of rejection in the elevated DSA group. All persistently elevated DSA were directed against HLA Class II DQ (6 of 14 patients) epitopes. Survival analysis and the significance of different HLA antigens remains ongoing. <h3>Conclusion</h3> The development of persistently elevated HLA Class II DQ DSA is associated with CLAD and likely decreased survival in the pediatric lung transplant population.

Impact of low-level pretransplant donor-specific antibodies on outcomes after kidney transplantation.

BackgroundThe effect of low‐level pretransplant donor‐specific antibody (DSA) on kidney transplant outcomes is not well described. The goal of this study was to compare outcomes among patients of varying immunologic risk, based on the level of pretransplant DSA.MethodsWe retrospectively reviewed all adult kidney transplant recipients who had undergone a transplant at our center between January 2013 and May 2017. Patients were grouped as negative DSA (mean fluorescence intensity, [MFISUM < 100]), low‐level DSA (MFISUM 100–1000), and positive DSA (MFISUM > 1000). Rejection, infection, graft, and patient survival were outcomes measured.ResultsOf 952 patients, 82.1% had negative DSA, 10.7% had low‐level DSA, and 7.1% had positive DSA. The positive DSA group had the highest rate of antibody‐mediated rejection (10.3%), followed by low‐level DSA (7.8%) and the negative DSA group (4.5%) (p = .034). The rate of BK viremia was highest in the positive DSA group (39.7%), followed by the low‐level group (30.4%) and the negative DSA group (25.6%), (p = .025). None of the other outcomes, including graft or patient survival, were different between the groups.ConclusionWhile low‐level DSA should not prevent proceeding with kidney transplantation, it should not be ignored. Future studies are needed to investigate the long‐term effects of varying levels of pre‐transplant DSA on outcomes.

Continuous Intermittent Intravenous Immunoglobulin in Heart Transplant Recipients with Elevated Donor-Specific Antibody Levels

<h3>Purpose</h3> Donor-specific antibodies (DSA) develop following heart transplantation (HT), and are associated with antibody-mediated rejection (AMR). However, treatment of persistently elevated DSA levels remains unclear. We aimed to evaluate the use of intermittent intravenous immunoglobulin (IVIg) for the treatment of elevated DSA. <h3>Methods</h3> We identified all adult HT recipients receiving monthly IVIg infusions between September 2019 and October 2020. Patient information including serial DSA levels, as well as hemodynamic and echocardiographic characteristics, were collected from the electronic health record. <h3>Results</h3> The cohort included 17 patients with a mean age of 57 +/- 15 years, 65% were male, & median time from HT was 48 months. 7 patients had prior biopsy-proven AMR, 7 had high mean fluorescence intensity (MFI) DSA alone, and 3 had allograft dysfunction without proven etiology. The average left ventricular ejection fraction (LVEF) prior to IVIg was 50% +/- 14%. Prior to intermittent IVIg 12 patients (71%) received an additional immunosuppressive agent (thymoglobulin, bortezomib, rituximab, belatacept), while 11 of them (65%) also received plasmapheresis. The mean duration of IVIg following pAMR was 7.6 +/- 7 months. DSA MFI decreased by 27% in patients with confirmed diagnosis of AMR and by 10% in those with elevated DSA alone after initiating intermittent IVIg (figure). Both LVEF and cardiac index improved in all three groups following initiation of IVIg infusions. Pulmonary capillary wedge pressure (PCWP) decreased in the elevated DSA and allograft dysfunction groups while it increased in the AMR group. Seven patients were admitted for suspected rejection after starting treatment. <h3>Conclusion</h3> DSA MFI declined and LVEF improved following initiation of intermittent IVIg infusions. Further study is needed to determine whether IVIg can prevent <i>de novo</i> or recurrent AMR.

Crossing low/moderate-level donor-specific antibodies during heart transplantation.

Donor-specific antibodies (DSAs) in patients prior to heart transplantation are associated with increased risk of rejection and can lead to longer waitlist times, but it is not known whether patients with low/moderate-level DSA at transplant have acceptable post-transplant outcomes. We performed a single-center, retrospective review to examine outcomes associated with crossing pre-existing low/moderate-level DSA. We assessed 864 patients awaiting heart transplantation between 2010 and 2018, identified 67 patients with low/moderate-level DSA and compared them to patients who were sensitized without DSA at the time of heart transplantation, as well as a control group of non-sensitized patients. Outcomes included 3-year survival, freedom from cardiac allograft vasculopathy (CAV), freedom from non-fatal major adverse cardiac events (NF-MACE), and 1-year freedom from rejection. In the first-year post-transplant, there was decreased freedom from antibody-mediated rejection (AMR) in the patients with pre-existing DSA compared with patients sensitized without DSA and non-sensitized patients. However, the DSA group experienced similar 3-year post-transplant survival, freedom from CAV, and freedom from NF-MACE compared with the other study groups. Our findings suggest that crossing low/moderate-level DSA does not lead to worse outcomes in heart transplantation and may offer a viable way to increase a sensitized patient's chance to obtain a suitable donor.

HLA Matching in Cardiac Transplantation - Impact on Cardiac Allograft Vasculopathy, Rejection and Donor Specific Antibodies

Introduction HLA matching is not current practice in heart transplant (HT) donor allocation due to scarcity of donor organs and ischemic time. However HLA mismatch might adversely affect transplant outcomes. Even if HLA matching is not possible the degree of HLA mismatch might help inform clinicians on a patients risk for long term transplant complications. Hypothesis We hypothesize that the degree of HLA mismatch affects long-term complications in a stable HT cohort. Methods 65 clinically stable HT recipients (no cellular (ACR) or antibody mediated rejection (AMR) in the preceding 6 months) ≥ 2 years post transplant were enrolled. Serologic HLA typing was obtained for donor and recipients (D/R) pairs and the number of matches was analyzed combined for HLA class I and HLA II. Study endpoints were donor specific antibody (DSA) formation and significant cardiac allograft vasculopathy (CAV). Results HLA-A,-B,-C, -DR and-DQ (ABCDRQ) typing were available for 37 D/R pairs and were analyzed for matches. Additionally, 53 D/R pairs had HLA-A,-B, -DR (ABDR) typing. Meantime post HT was 8.5±5.4 years. A total of 28 patients had CAV and 9 patients had DSA. Among the ABCDRDQ cohort the number of matches was 1.54 ± 1.17 and 1.00 (0.00-1.00) in the ABDR cohort. There were no differences in the number of HLA matches for both cohorts among those with and without DSA and those with and without CAV (Table).However among the ABCDRDQ cohort there was a trend towards higher number of HLA matches in those without DSA 1.63 ± 1.19 versus 1.14 ± 1.07 in the DSA group (p 0.32), this was likely limited by the small sample size.There was no significant relationship between total HLA matches and number of ACR episodes (p 0.89). The incidence of AMR was too low for analysis. Conclusion In this highly selected cohort of clinically stable long time transplant survivors the degree of serological HLA matching was not associated with the development of CAV or ACR. However, there was a trend towards less DSA formation in those with more D/R HLA matches. Future longitudinal studies should evaluate the development of long-term complications as a function of HLA matching and potentially incorporate HLA mismatch as an indicator for the need of enhanced clinical surveillance.

Crossing Low Level Donor-Specific Antibody at the Time of Heart Transplantation May Save Lives

Purpose Sensitization is an increasing problem for patients (pts) awaiting heart transplant (HTx) partly due to increased requirement for bridging with mechanical support, a risk factor for sensitization. In order to widen the donor pool for sensitized pts, our program has decided to cross low-level donor-specific antibody (DSA) at HTx. We assessed the long-term outcome of these pts. Methods Between 2010-13, we reviewed 352 HTx pts in our single-center program and identified 31 pts transplanted against a low-level DSA (MFI Results The 31 pts transplanted against a low-level DSA had significantly less freedom from first-year AMR compared to control group. However, the low-level DSA group had significantly better 5-year survival. There was no significant difference in freedom from 1-year ATR or ACR and 5-year freedom from CAV compared to control group. There was a trend for better 5-year freedom from NF-MACE in the low-level DSA group compared to control group (see table). Conclusion Crossing low-level DSA at HTx appears to have acceptable outcomes despite increased risk of first-year AMR. This strategy can expand the donor pool and potentially save lives. The survival benefit in the low-level DSA group may represent eventual accommodation however further studies are needed.

Does Cell-Free DNA Detect the Development of De Novo Donor Specific Antibodies

Purpose Donor Derived Cell-Free DNA (dd-cfDNA) has been demonstrated to detect both cellular and antibody mediated rejection after heart transplantation (Htx). The development of donor-specific antibodies (DSA) suggests that the recipient's immune system recognizes that the donor heart as foreign and develops antibodies against it. It is not clear whether the DSA is actually causing harm to the donor heart resulting in an increase in dd-cfDNA. Methods Between 2015-2017 we identified 24 stable HTx patients with dd-cfDNA draws in the first year who developed de novo DSA. In our program, blood is routinely drawn for DSA at 1,3,6 and 12 months after HTx. This group of patients with dd-cfDNA level (drawn within 1-month of a positive DSA result), was compared to a group of patients with dd-cfDNA levels (drawn within 1-month of a negative DSA result). All dd-cfDNA draws were from patients with normal endomyocardial biopsies and normal echocardiographic LVEF. Results The average dd-cfDNA for the DSA group was 1.2% which was significantly elevated compared to the dd-cfDNA of the control group with negative DSA which was 0.4%. The mean DSA level defined as mean fluorescent intensity (MFI) level was 6,984 ± 4,460. (MFI range 5,000 to 17,500). Conclusion dd-cfDNA appears to be correlated to the development of DSA. Furthermore, it suggests that DSA may be injuring the donor heart and may necessitate treatment of these patients.

Effect of Preformed or De Novo Anti-HLA Antibodies on Function and Graft Survival in Kidney Transplant Recipients.

BackgroundDonor-specific antibodies (DSA), directed against human leucocyte antigens (HLA), are associated with increased risk for graft rejection in kidney transplantation. Anti-HLA antibodies detection by Luminex™ present high sensitivity and accuracy, but its interpretation after transplantation is not completely clear.The aim of this study was to evaluate the impact of anti-HLA antibodies, preformed or de novo, on renal function, graft survival, and incidence of antibody-mediated acute rejection (AMR).Material/MethodsA retrospective cohort of 86 kidney transplant recipients was divided into 3 groups according to the presence of anti-HLA antibodies before transplantation: donor-specific antibodies (DSA+, n=15), non-DSA (non-DSA, n=39), and negative pre-transplant panel reactive antibodies (PRA) that became positive after transplantation (PRA−, n=22). Forty-nine recipients with negative PRA pre- and post-transplantation were excluded. Antibody specificity and intensity of fluorescence (MFI) and their relationship with renal function, proteinuria, AMR, and graft failure were evaluated.ResultsAmong patients who completed 1 year of follow-up, there was no significant difference in serum creatinine, estimated glomerular filtration rate, or proteinuria. AMR incidence was 9.5% in the DSA group, 2.3% in the non-DSA group, and 9.1% in the PRA− group. There was no correlation between fluorescence intensity and/or antibodies class (I or II) with increased risk of AMR. Thirteen grafts failed within 1 year post-transplant, there were 9 deaths due to infection, and only 1 due to AMR (PRA− group, DSA de novo at 3 months).ConclusionsIn contrast to previous reports, we did not find a correlation between incidence of AMR and MFI intensity in this series.

High Prevalence of Post-Transplant Donor Specific HLA-DQ Antibody in Live Related Renal Transplantation

Purpose The aim of this study was to determine the HLA classes of post-transplant donor specific antibody (DSA) in live related renal transplant recipient. Patients and Method HLA antibodies were analyzed in 212 renal transplant recipient, <3 to 36 months post-transplant. Samples were collected in routine follow-up in out-patient clinic. All recipients had stable graft function in the last 6 months. HLA antibody was negative by flow cross match and Luminex pre-transplant. All rejections were confirmed by biopsy. Antibody screen and single antigen screen was undertaken by Luminex. Outcomes were compared between recipient with DSA and No DSA for rejection, HLA match, Serum Creatinine and Graft Survival. Results Of the 212 recipient screened for HLA antibodies 20 (9.4%) were positive for Class I and 34 (16%) for Class II. DSA were found in 31 (14.6%). DSA developed in 2 (7%) of the recipient within 3 months, in 4 (14%) within 6 and 25 (79%) after 6 months. DSA against Class I in 10 (4.7%) and Class II in 27 (13%). Within Class I, against HLA A in 9 (90%) and HLA B 1 (10%), while within Class II, HLA-DR in 11 (41%), HLA-DQ in 15 (55%) and HLA-DR + HLA-DQ in 1 (3.7%). Rejections were diagnosed in 16 (52%) of DSA group vs 48 (26%) in No DSA group (p< 0.05). The mean HLA match was 3.39 ± 0.9 in DSA vs 3.67 ± 1.2 in Non DSA (p 0.231). The mean S. Creatinine was 2.42 ± 1.4 mg/dl in DSA vs 1.6 ± 0.8 in Non DSA (p 0.001). Graft survival in DSA group at 1 and 5 years was 100%, 71% vs 100% and 94% in the No DSA group, (p< 0.009). Conclusion In OPD follow-up 14.6% of the recipient had DSA mainly against Class II HLA-DQ antigens. Rejection episodes were higher in patients with DSA and graft survival was poorer as compared to Non DSA group. High frequency of HLA-DQ antibodies warrant typing for HLA-DQ as routine specially in live related transplant to determine the long term consequences of DSA against HLA-DQ antigens and their management.

Complement (C1q) Binding De Novo Donor-Specific Antibodies and Cardiac-Allograft Vasculopathy in Pediatric Heart Transplant Recipients.

We hypothesized C1q binding de novo donor-specific antibody (DSA) after heart transplant (HT) is a higher risk for development of coronary artery vasculopathy (CAV) in children. A retrospective analysis of 127 pediatric HT recipients transplanted between January 2005 and December 2014 was used to determine complement (C1q)-binding de novo DSA on the outcomes of HT and the ability of the C1q assay to predict CAV development. Of 127 patients, 59 (46.4%) developed de novo DSA, 37 of those had C1q+ DSA. There was no difference in baseline characteristics except patients who developed C1q+ DSA more often received a donor heart from a female compared with C1q- DSA group (P = 0.034). The DSA median fluorescent intensity (MFI) value of 7000 or greater had 80% sensitivity and 80% specificity (C statistics 0.89, P <0.05) for predicting positive C1q binding. Multivariate analyses identified C1q binding DSA as an independent risk for CAV with a hazard ratio (HR) of 3.25 (95% confidence interval [CI], 1.33-7.93; P = 0.0095). In multivariable Cox proportional hazard models, the covariates associated with graft loss included: C1q+ DSA (HR, 3.2; 95% CI, 1.34-7.86; P < 0.009), pre-HT renal insufficiency (HR, 11.3; 95% CI, 3.71-34.29; P < 0.0001), and pre-HT ventilator support (HR, 3.3; 95% CI, 1.39-7.81; P = 0.007). The DSA strength in MFI correlates with positive C1q-binding activity and hence functional capabilities of DSA. Close monitoring of DSA strength in MFI and function (C1q assay) may be useful for identifying pediatric HT recipient at risk for development of CAV.

Deleterious impact of C3d-binding donor-specific anti-HLA antibodies after pediatric liver transplantation

BackgroundThe prevalence and clinical impact of anti-HLA donor-specific antibodies (DSA) after liver transplantation (LT) have not been extensively studied, especially in pediatric population. MethodsThe present cross-sectional study included 100 patients who underwent a first LT in childhood. Anti HLA immunization study was performed at a single time point during routine follow-up using Luminex® single antigen tests with classical anti-IgG conjugate and anti-C3d conjugate. ResultsThe main indication for LT was biliary atresia (52%) and median age at LT was 4.6years. The median time between LT and DSA assessment was 7.8years (range 1–21years). DSA was identified in twenty-four patients (24%) after LT, with a prevalence of 8%, 28%, 33%, 50%, respectively 0–5years, 5–10years, 10–15years and >15years after LT. DSA were mainly class II (23/24) with a mean MFI of 9.731±5.489 and 18 (79.3%) were C3d-binding DSA. Multivariate analysis disclosed that time elapsed since LT (p<0.01) and history of fulminant hepatitis (p=0.04) were significantly associated with a higher rate of DSA. Liver function tests (at time of DSA assessment) were not different according to the presence or not of DSA (or C3d-binding DSA). Regarding histology, the DSA group had a higher rate of chronic rejection, cirrhosis and centrilobular fibrosis or cirrhosis. In addition, patients with C3d-binding DSA and high MFI (>10,000) had a significant poorer long-term graft survival (p=0.03). ConclusionIn our pediatric cohort of LT, prevalence of DSA was high and increased regularly with time. Presence of C3d positive-DSA with high MFI was associated with a higher rate of graft loss.

Impact of Donor-Specific Antibodies on Graft Fibrosis After Pediatric Living Donor Liver Transplantation for Biliary Atresia

BackgroundPediatric living donor liver transplant (LDLT) patients sometimes develop graft fibrosis after non-recurrent diseases such as biliary atresia (BA). Donor-specific antibodies (DSA) have recently been shown to play a possible role in graft damage after liver transplantation. We report the impact of DSA on pediatric LDLT for BA patients. MethodsPatients under age 18 years who received LDLT for BA at our institution and who had at least 5 years' follow-up were identified, and 23 were eventually enrolled in this study. Pathological findings were assessed with the use of the last available biopsy. Patients were divided into 2 groups, DSA-positive and DSA-negative. Graft fibrosis after LDLT was assessed according to DSA groups. ResultsThe mean patient age at transplant was 2.6 years. The mean time to the last available biopsy after LDLT was 8.2 years (4.8–15.6 years); 6 patients (26%) showed no fibrosis, whereas fibrosis was graded as F1, F2, or F3 in 8 patients (35%), 8 patients (35%), and 1 patient, respectively. DSA were observed in 12 patients (52%). Moderate graft fibrosis (F2 and F3) was found in 7 (58%) of the DSA-positive group, but only 2 (18%) of the DSA-negative group, showing a statistically significant difference (P < .05). Pre-transplant cross-matching was performed in 17 patients. The 2 patients with a positive cross-match were DSA-positive. Six cross-match–negative patients developed de novo DSA after LDLT. ConclusionsGraft fibrosis was observed after LDLT for BA during long-term follow-up, more commonly in DSA-positive patients. DSA may play a role in fibrosis formation.

Role of Pretransplant Complement-fixing Donor-specific Antibodies Identified by C1q Assay in Kidney Transplantation

BackgroundKidney transplant recipients who have pretransplant donor-specific human leukocyte antigen (HLA) antibodies have greater risk for developing allograft rejection and allograft loss. However, there is a varied effect of graft injury among patients with pretransplantation donor-specific antibodies (DSA). The difference of complement activating ability may be the reason why some DSA are detrimental to kidney allograft. This study aimed to investigate the association between pretransplantation C1q-binding DSA and clinical outcomes. MethodsThis retrospective study included 48 pretransplant sera from kidney transplant recipients who had pretransplant DSA with negative complement-dependent cytotoxic (CDC) crossmatches. The IgG DSA testing and C1q testing were performed on a Luminex platform with single antigen bead assay. The clinical outcomes between C1q-positive and C1q-negative groups were compared. ResultsC1q-positive DSA were detected in 12 out of 48 patients (25%). The incidences of antibody-mediated rejection (AMR) were higher among patients with C1q-positive DSA than patients with C1q-negative DSA (66.7% vs 41.7%). Nevertheless, there were no statistically significant associations between C1q-DSA and AMR (odds ratio 2.8, 95% CI 0.68–11.6, P = .13) and between C1q-DSA and graft loss (odds ratio 0.52, 95% CI 0.09–2.89, P = .44). The C1q-positive DSA group had significantly higher IgG DSA MFI than the C1q-negative DSA group (P < .001). ConclusionC1q-binding ability of DSA in pretransplant sera of kidney recipients was not associated with antibody-mediated rejection and graft loss post-transplantation. In contrast with the clinical relevance of C1q testing in the post-transplantation setting, C1q testing in pretransplant sera has limited use for immunological risk assessment.

Outcome after Desensitization in HLA or ABO-Incompatible Kidney Transplant Recipients: A Single Center Experience

BackgroundThe shortage of deceased donors led to an increase of living donor kidney (LDK) transplantations performed in the presence of donor-specific antibodies (DSA) or ABO incompatibility (ABOi) using various desensitization protocols.MethodsWe herein analyzed 26 ABOi and 8 Luminex positive DSA patients who were successfully desensitized by anti-CD20, antigen-specific immunoadsorption and/or plasmapheresis to receive an LDK transplant. Twenty LDK recipients with non-donor-specific HLA-antibodies (low risk) and 32 without anti-HLA antibodies (no risk) served as control groups.Results1-year graft survival rate and renal function was similar in all 4 groups (creatinine: 1.63 ± 0.5 vs 1.78 ± 0.6 vs 1.64 ± 0.5 vs 1.6 ± 0.3 mg/dl in ABOi, DSA, low risk and no risk group). The incidence of acute T-cell mediated rejections did not differ between the 4 groups (15% vs 12, 5% vs 15% vs 22% in ABOi, DSA, low risk and no risk), while antibody-mediated rejections were only found in the DSA (25%) and ABOi (7.5%) groups. Incidence of BK nephropathy (BKVN) was significantly more frequent after desensitization as compared to controls (5/34 vs 0/52, p = 0.03).ConclusionWe demonstrate favorable short-term allograft outcome in LDK transplant recipients after desensitization. However, the desensitization was associated with an increased risk of BKVN.

Renal transplantation across the donor-specific antibody barrier: Graft outcome and cancer risk after desensitization therapy.

Desensitization regimens including use of intravenous immune globulin and rituximab have been reported to overcome renal transplant hyperacute rejection. A retrospective case-control study was performed to assess the results and complications of renal transplantation with desensitization therapy for donor-specific antibody (DSA) in a transplant center in Asia, where donor exchange was usually not allowed. Between January 2007 and December 2013, 22 patients with DSA received live-donor renal transplantation after desensitization (DSA group). During the same period, the DSA group was compared to the NSA group (152 renal transplants) who had no specific antibody to the donors (66 from deceased donors and 86 from living relatives). Rejection, renal function, graft and patient survival rates, infection, and cancer incidence were reviewed and analyzed from medical records. The DSA group (46.8%) had significantly higher acute rejection rates than the NSA group (13.7%) at the 1-year follow-up. The estimated renal function, 5-year graft, and patient survival rates were comparable between the groups. The DSA group (19.6%) had significantly higher 5-year de novo cancer incidence than the NSA group (8.5%; p=0.028); three patients of the DSA group developed urothelial carcinoma 17.0±3.0 months after transplantation. By using stepwise Cox regression analysis, desensitization therapy was identified as the sole independent risk factor for post-transplant urothelial carcinoma. When compared to renal transplantation without DSA, desensitization therapy for DSA resulted in equivalent renal transplant outcome but potentially increased risk of urothelial carcinoma after transplantation.

Strength of Donor-Specific Antibodies With the Use of Luminex Single-Antigen Beads Is a Reliable Predictor of Acute Rejection in Living-Relative Kidney Recipients

BackgroundLuminex single-antigen assay is a promising technique for determination of donor-specific antibodies (DSAs) in renal transplantation. MethodsSerum samples from living-relative renal recipients before and after renal transplantation were examined with the use of Luminex single-antigen assay. The impact of de novo DSAs on the early clinical outcomes of renal allograft was analyzed. ResultsOf the 61 patients included, 15 patients (24.6%) presented de novo DSA (4 class I, 4 class II, and 7 both classes) after transplantation, and the average (median) cumulative strength of DSA was 1,283 (range, 0–10,802) mean fluorescence index (MFI) for class I versus 1,324 (range, 0–14,985) MFI for class II (P > .05). Twelve (19.7%) of the 61 patients experienced a clinical/subclinical acute rejection (AR) episode within the 1st 2 years after transplantation. A clinical/subclinical AR episode was diagnosed in 40% of DSA(+) patients and 13.0% of DSA(−) patients (P < .05). DSA(+) patients who developed an AR episode had a higher mean cumulative MFI value (8,118.3 ± 5,287.4; range, 1,785–14,985) than patients who did not develop an AR episode (3,283.7 ± 2,601.0; range, 786–8,113; P < .05). Serum creatinine levels in the DSA(+) group were significantly higher than in the DSA(−) group at 12 and 24 months after transplantation. The graft survival rates at 2 years in the DSA(+) and DSA(−) groups were not different (86.7% vs 91.3%; P > .05). ConclusionsPatients with de novo DSAs at high strength may suffer a high risk of developing an AR episode. Therefore, careful monitoring of de novo DSAs with the use of Luminex single-antigen beads may help in early intervention for AR in renal allografts and to minimize renal damage caused by the antibodies.