Novo Donor Specific Antibodies Research Articles

(619) - De Novo Donor Specific Antibodies is Associated with Death from Graft Failure in Lung Transplantation

(619) - De Novo Donor Specific Antibodies is Associated with Death from Graft Failure in Lung Transplantation

(620) - Association of Donor-Derived Cell-Free DNA Levels with the Development of De Novo Donor-Specific Antibodies and Risk of Death in Lung Transplant Recipients

(620) - Association of Donor-Derived Cell-Free DNA Levels with the Development of De Novo Donor-Specific Antibodies and Risk of Death in Lung Transplant Recipients

Impact of HLA Eplet Mismatch on De Novo Donor Specific Antibody Formation After Kidney Transplantation

HLA eplet mismatching is an alternative approach to assess the risk of developing de novo donor-specific antibodies (dnDSA) in kidney transplantation. This strategy may offer more precise risk stratification than conventional approaches. This study aimed to find the association between HLA eplet mismatches and dnDSA formation in Thai kidney transplant recipients. A retrospective cohort study of kidney transplant recipients transplanted between 2000 and 2021 at Ramathibodi Hospital was performed. Recipients with pretransplant panel reactive antibody >0% or without DSA testing post-transplant were excluded. One hundred fifty recipients were included in the final study. High-resolution HLA typing was imputed by the HaploStat application. HLA eplet mismatch analysis was conducted using HLAMatchmaker. The association between the number of eplet mismatches and the risk of dnDSA formation was assessed by Cox regression analysis. Of 150 recipients, 43 were dnDSA-positive, and 107 were dnDSA-negative patients. Compared with the dnDSA-negative group, patients with class II dnDSA had significantly more HLA-DR/DQ antibody (Ab)-verified eplet mismatches (6 [IQR 4-8] vs 4 [IQR 1-7], P = .045). The receiver operating characteristics analysis showed that the HLA-DQ Ab-verified eplet mismatches ≥2 were the best predictive of HLA class II dnDSA development. The number of HLA-DQ Ab-verified eplet mismatches ≥2 had the highest hazard rate of HLA class II dnDSA occurrence (adjusted HR, 3.74; 95%CI, 1.24-11.24, P = .019). HLA-DQ Ab-verified eplet mismatches are significantly associated with class II dnDSA development. Our data supports the utility of HLA eplet mismatching for donor-recipient risk assessment.

Tacrolimus's Time Below Therapeutic Range Is Associated With Acute Pancreatic Graft Rejection and the Development of De Novo Donor-specific Antibodies.

Tacrolimus is pivotal in pancreas transplants but poses challenges in maintaining optimal levels due to recipient differences. This study aimed to explore the utility of time spent below the therapeutic range and intrapatient variability in predicting rejection and de novo donor-specific antibody (dnDSA) development in pancreas graft recipients. This retrospective unicentric study included adult pancreas transplant recipients between January 2006 and July 2020. Recorded variables included demographics, immunosuppression details, HLA matching, biopsy results, dnDSA development, and clinical parameters. Statistical analysis included ROC curves, sensitivity, specificity, and predictive values. A total of 131 patients were included. Those with biopsy-proven acute rejection (BPAR, 12.2%) had more time (39.9% ± 24% vs. 25.72% ± 21.57%, p = 0.016) and tests (41.95% ± 13.57% vs. 29.96% ± 17.33%, p = 0.009) below therapeutic range. Specific cutoffs of 31.5% for time and 34% for tests below the therapeutic range showed a high negative predictive value for BPAR (93.98% and 93.1%, respectively). Similarly, patients with more than 34% of tests below the therapeutic range were associated with dnDSA appearance (38.9% vs. 9.4%, p = 0.012; OR 6.135, 1.346-27.78). In pancreas transplantation, maintaining optimal tacrolimus levels is crucial. Suboptimal test percentages below the therapeutic range prove valuable in identifying acute graft rejection risk.

De Novo Donor-Specific Antibodies after Heart Transplantation: A Comprehensive Guide for Clinicians

Antibodies directed against donor-specific human leukocyte antigens (HLAs) can be detected de novo after heart transplantation and play a key role in long-term survival. De novo donor-specific antibodies (dnDSAs) have been associated with cardiac allograft vasculopathy, antibody-mediated rejection, and mortality. Advances in detection methods and international guideline recommendations have encouraged the adoption of screening protocols among heart transplant units. However, there is still a lack of consensus about the correct course of action after dnDSA detection. Treatment is usually started when antibody-mediated rejection is present; however, some dnDSAs appear years before graft failure is detected, and at this point, damage may be irreversible. In particular, class II, anti-HLA-DQ, complement binding, and persistent dnDSAs have been associated with worse outcomes. Growing evidence points towards a more aggressive management of dnDSA. For that purpose, better diagnostic tools are needed in order to identify subclinical graft injury. Cardiac magnetic resonance, strain techniques, or coronary physiology parameters could provide valuable information to identify patients at risk. Treatment of dnDSA usually involves plasmapheresis, intravenous immunoglobulin, immunoadsorption, and ritxumab, but the benefit of these therapies is still controversial. Future efforts should focus on establishing effective treatment protocols in order to improve long-term survival of heart transplant recipients.

Clinical Outcome of Kidney Transplant Recipients with C1q-Binding De Novo Donor Specific Antibodies: A Single-Center Experience.

Complement activation by HLA antibodies is a key component of immune-mediated graft injury. We examined the clinical outcomes of kidney transplant recipients with complement-fixing de novo donor-specific antibodies (dnDSA) who were followed in our center. The C1q-binding ability was retrospectively assessed in 69 patients with dnDSA and mean fluorescence intensity (MFI) values > 2000 out of the 1325 kidney transplant recipients who were screened for DSA between 2015 and 2019. Luminex IgG single antigen beads (SAB)and C1q-SAB assays (One Lambda) were used. C1q-binding dnDSA was identified in 32/69 (46.4%) of the patients. Significantly higher MFI values were observed in C1q-positive DSA (18,978 versus 5840, p < 0.001). Renal graft biopsies were performed in 43 of the kidney transplant recipients (62.3%) with allograft dysfunction. Antibody-mediated rejection (ABMR) was detected in 29/43 (67.4%) of the patients. The incidence of ABMR was similar among patients with C1q-binding and non-C1q-binding DSA (51.7% vs. 48.3%, p = 0.523). Graft loss occurred in 30/69 (43.5%) of the patients at a median time of 82.5 months (IQR 45-135) from DSA detection. C1q-binding DSA was present in more patients who experienced graft loss (53.1% vs. 35.1%, p = 0.152). Higher MFI values and inferior clinical outcomes occurred in most of the kidney transplant recipients with C1q-binding dnDSA.

Comparison of high-dose IVIG and rituximab versus rituximab as a preemptive therapy for de novo donor-specific antibodies in kidney transplant patients

De novo donor-specific antibody (dnDSA) is associated with a higher risk of kidney graft failure. However, it is unknown whether preemptive treatment of subclinical dnDSA is beneficial. Here, we assessed the efficacy of high-dose intravenous immunoglobulin (IVIG) and rituximab combination therapy for subclinical dnDSA. An open-label randomized controlled clinical trial was conducted at two Korean institutions. Adult (aged ≥ 19 years) kidney transplant patients with subclinical class II dnDSA (mean fluorescence intensity ≥ 1000) were enrolled. Eligible participants were randomly assigned to receive rituximab or rituximab with IVIG at a 1:1 ratio. The primary endpoint was the change in dnDSA titer at 3 and 12 months after treatment. A total of 46 patients (24 for rituximab and 22 for rituximab with IVIG) were included in the analysis. The mean baseline estimated glomerular filtration rate was 66.7 ± 16.3 mL/min/1.73 m2. The titer decline of immune-dominant dnDSA at 12 months in both the preemptive groups was significant. However, there was no difference between the two groups at 12 months. Either kidney allograft function or proteinuria did not differ between the two groups. No antibody-mediated rejection occurred in either group. Preemptive treatment with high-dose IVIG combined with rituximab did not show a better dnDSA reduction compared with rituximab alone.Trial registration: IVIG/Rituximab versus Rituximab in Kidney Transplant With de Novo Donor-specific Antibodies (ClinicalTrials.gov Identifier: NCT04033276, first trial registration (26/07/2019).

Genetic Polymorphisms in Follicular Helper T Cell–Related Molecules Predispose Patients to De Novo Donor-Specific Antibody Formation After Kidney Transplantation

Risk prediction of de novo donor-specific antibody (dnDSA) formation is crucial for understanding the long-term prognostic impact of kidney transplantation (KT). Recently, follicular helper T (Tfh) cells, a subtype of CD4+ T cells, have been reported to play an important role in dnDSA formation after solid organ transplantation. Given the growing recognition of the importance of Tfh cells in generating a strong humoral immune response, we examined whether polymorphisms in Tfh cell-related molecules were associated with dnDSA formation after KT. Eighty-three patients who underwent living-donor KT between January 2013 and February 2020 at Hiroshima University Hospital were included in the study. Six Tfh cell-related molecules (BCL6, CXCR5, CXCL13, ICOS, CD40L, and IL21) that are important for Tfh cell differentiation and maturation in secondary lymphoid tissues were investigated. CTLA4, which is important for Tfh-cell activation, was also investigated. Single nucleotide polymorphisms (SNPs) in the genes for these molecules were detected using Taq Man SNP genotyping and evaluated for their association with dnDSA formation after KT. Of the 83 KT recipients, 8 developed dnDSAs during the observation period. No statistically significant differences were observed in the baseline characteristics between patients with and without dnDSA formation, except for donor age. Among the 7 Tfh cell-related molecules, the incidence of dnDSA formation was associated with CXCR5 and CTLA4 SNPs. Furthermore, combining these 2 SNPs enabled more significant stratification of dnDSA formation. Our findings indicate that genetic polymorphisms in Tfh cell-related molecules are predisposing factors for dnDSA formation after KT.

(150) Trends in HeartCare Values Following the Development of De Novo Donor Specific Antibodies

(150) Trends in HeartCare Values Following the Development of De Novo Donor Specific Antibodies

(354) De Novo Donor Specific Antibodies and Late Graft Dysfunction: Another Reason to Treat Before the Damage is Done?

(354) De Novo Donor Specific Antibodies and Late Graft Dysfunction: Another Reason to Treat Before the Damage is Done?

HLA-DR/DQ Single Molecule Eplet Mismatch and Formation of De Novo Donor-Specific Anti-HLA Antibodies After Kidney Transplantation in Children

HLA-DR/DQ Single Molecule Eplet Mismatch and Formation of De Novo Donor-Specific Anti-HLA Antibodies After Kidney Transplantation in Children

Patterns in Tacrolimus Variability and Association with De Novo Donor-Specific Antibody Formation in Pediatric Kidney Transplant Recipients.

High tacrolimus intrapatient variability has been associated with inferior graft outcomes in patients with kidney transplants. We studied baseline patterns of tacrolimus intrapatient variability in pediatric patients with kidney transplants and examined these patterns in relation to C1q-binding de novo donor-specific antibodies. All tacrolimus levels in participants who underwent kidney-only transplantation at a single pediatric center from 2004 to 2018 (with at least 12-month follow-up, followed until 2019) were analyzed to determine baseline variability. Intrapatient variability was defined using the coefficient of variation (SD/mean ×100%) of all samples in a 6-month moving window. Routine de novo donor-specific antibody measurements were available for a subgroup of patients transplanted in 2010-2018. Cox proportional hazards models using tacrolimus intrapatient variability as a time-varying variable were used to examine the association between intrapatient variability and graft outcomes. The primary outcome of interest was C1q-binding de novo donor-specific antibody formation. Tacrolimus intrapatient variability developed a steady-state baseline of 30% at 10 months post-transplant in 426 patients with a combined 31,125 tacrolimus levels. Included in the outcomes study were 220 patients, of whom 51 developed C1q-binding de novo donor-specific antibodies. De novo donor-specific antibody formers had higher intrapatient variability, with a median of 38% (interquartile range, 28%-48%) compared with 28% (interquartile range, 20%-38%) for nondonor-specific antibody formers (P<0.001). Patients with high tacrolimus intrapatient variability (coefficient of variation >30%) had higher risk of de novo donor-specific antibody formation (hazard ratio, 5.35; 95% confidence interval, 2.45 to 11.68). Patients in the top quartile of tacrolimus intrapatient variability (coefficient of variation >41%) had the strongest association with C1q-binding de novo donor-specific antibody formation (hazard ratio, 11.81; 95% confidence interval, 4.76 to 29.27). High tacrolimus intrapatient variability was strongly associated with de novo donor-specific antibody formation.

Combined Analysis of HLA Class II Eplet Mismatch and Tacrolimus Levels for the Prediction of De Novo Donor Specific Antibody Development in Kidney Transplant Recipients.

We investigated whether HLA class II eplet mismatch was related to dnDSA development and analyzed its combined impact with tacrolimus levels for kidney transplantation outcomes. A total of 347 kidney transplants were included. HLA Matchmaker was used for the single molecular eplet, total eplet, antibody (Ab)-verified eplet mismatch analyses, and Ab-verified single molecular analysis to identify HLA-DR/DQ molecular thresholds for the risk of dnDSA development. A time-weighted tacrolimus trough level (TAC-C0) of 5 ng/mL and a TAC-C0 time-weighted coefficient variability (TWCV) of 20% were applied to find the combined effects on dnDSA development. A high level of mismatch for single molecular eplet (DQ ≥ 10), total eplet (DQ ≥ 12), Ab-verified eplet (DQ ≥ 4), and Ab-verified single molecular eplet (DQ ≥ 4) significantly correlated with HLA class II dnDSA development. Class II dnDSA developed mostly in patients with low TAC-C0 and high eplet mismatch. In the multivariable analyses, low TAC-C0 and high eplet mismatch showed the highest hazard ratio for the development of dnDSA. No significant combined effect was observed in dnDSA development according to TWCV. In conclusion, the determination of HLA class II eplet mismatch may improve the risk stratification for dnDSA development, especially in conjunction with tacrolimus trough levels.

Belatacept Treatment of Recurrent Late-onset T Cell-mediated Rejection/Antibody-mediated Rejection With De Novo Donor-specific Antibodies in a Liver Transplant Patient.

Background.T cell–mediated rejection that appears and persists late after transplantation is often associated with development of de novo donor-specific antibodies. Treatment of this condition often presents a conundrum because of the uncertainty regarding the trade-off between immunosuppression-related toxicities/complications and restoration of allograft function and structure.Methods.Herein, we report an illustrative case of a young 20-y-old otherwise healthy woman who underwent liver replacement for Alagille’s syndrome from an ABO-compatible, 6 antigen-mismatched crossmatch-negative 24-y-old man. Although triple baseline immunosuppression was used (tacrolimus, mycophenolate mofetil, and prednisone), she developed rejection 3 d after liver replacement. Despite verified continual immunosuppression compliance, 1.5 y after liver replacement she experienced 6 more rejection episodes over the following 18 mo and development of de novo donor-specific antibody.Results.Treatment with belatacept began 3.5 y after transplantation, normalizing her liver tests with no further rejections. A biopsy obtained 6 y after transplantation (postoperative day 2221) was normal, appearing without inflammation or residual fibrosis.Conclusions.Belatacept may be a useful treatment approach in this setting.

Development of De Novo Donor Specific Antibodies Following COVID-19 Vaccination in Cardiac Transplant

PurposeSome transplant patients mount an insufficient response to standard COVID-19 vaccine (COVAX) dosing and a booster dose has now been approved. Vaccination carries the theoretical risk of stimulating antibody production to the donor. There are no prior studies surveying de novo donor specific HLA antibodies (dnDSA) after COVAX. HLA-DQ is the most common dnDSA post cardiac transplant and is associated with worse outcomes. We reviewed the development of dnDSA to HLA-DQ in cardiac transplant patients after COVAX.MethodsDSA testing (luminex single antigen bead) was performed routinely at the time of surveillance endomyocardial biopsy. We retrospectively recorded any dnDSA to HLA-DQ with MFI >1000 after COVAX. We further identified a historical cohort (pre vaccination) of 32 patients who had DSA testing a minimum of 5 months after transplant.Results32 adult patients completed COVAX (16 Pfizer-BioNTech, 8 Moderna, 8 Johnson and Johnson) 3-79 mths after transplantation. 16 patients had DSA testing 1-5 mths post COVAX (4-84 mths post transplant) (Table 1). Three patients (18.8 %) demonstrated dnDSA to HLA-DQ (MFI 6360-25,824) 10-20 weeks post COVAX and all had episodes of high grade acute cellular rejection. One additional patient had rejection post COVAX without dnDSA. All 3 patients with dnDSA had robust response to the vaccine with antibodies to spike protein RBD of > 200 U/ml (Elecsys®). Eight vaccinated patients without dnDSA had anti-RBD testing, half had titres > 200 U/ml. In the historical pre COVAX cohort, 3 patients (9 %) demonstrated dnDSA (2022-25480 MFI), one of these had cellular rejection and one developed antibody mediated rejection.ConclusionOne fifth of cardiac transplant recipients developed dnDSA in the weeks following COVAX, all associated with rejection. While no definitive conclusions may be drawn, we believe these data suggest the need for immunological surveillance after COVAX. This may be even more important after a booster dose.

De Novo Donor Specific Antibody Expression in Lung Transplant Recipients with EVLP-Conditioned Allografts

<h3>Purpose</h3> Recipients of marginal donor lungs conditioned by ex-vivo lung perfusion (EVLP) have non-inferior short and long-term outcomes compared to recipients of non-EVLP lungs. Whether EVLP increases the risk of de novo donor specific anti-HLA antibodies (dnDSA) early post-transplant has not been reported. <h3>Methods</h3> We performed a single-center, retrospective analysis between 10/2019- 7/2021. EVLP was performed at a specialized center (Lung Bioengineering). Post-lung transplant (LTx) management was similar in both groups. DSA was measured at 1-month post-LTx using a Luminex single-antigen assay. Differences in baseline variables between groups were analyzed using Fisher's exact, Wilcoxon rank-sum or Kruskal-Wallis tests. Multiple logistic regression analysis was then performed to assess the relationship between EVLP and dnDSA, including covariates that were significant on univariate assessment at p<0.2. <h3>Results</h3> DSA were measured in 76 consecutive LTx recipients (LTRs) in the study period; 12 received EVLP-conditioned lungs and 64 did not. Baseline demographics were similar between cohorts except for total ischemic times (Fig 1). At 1-month post-LTx 3 patients (25%) in the EVLP cohort developed class II DSA (all DQ). In the non-EVLP cohort 6 patients (9%) developed class I DSA antibodies (all B) and 11 patients (17%) developed class II DSA (8 with DQ and 3 with DR). When adjusting for gram negative infection and transfused red blood cells, there was no difference in dnDNA incidence between cohorts (Fig 2). <h3>Conclusion</h3> The use of EVLP-conditioned donor lungs is not associated with increased incidence of dnDSA early post-LTx.

Is COVID Vaccine Associated with Development of De Novo Donor Specific Antibodies in Lung Transplant Recipients?

<h3>Purpose</h3> There have been sporadic reports of de novo donor-specific antibody (DSA) development post-COVID vaccine, causing a significant impact on the graft. The study aims to determine if the COVID vaccine increases the incidence of de novo DSA and antibody-mediated rejection. <h3>Methods</h3> This is a single-center retrospective cohort study of lung transplant recipients who received two doses of COVID vaccine between 1/1/2021 and 7/31/2021. Presence of de novo DSA was checked before and after COVID vaccine. This study was IRB-approved. Baseline demographic data were extracted. <h3>Results</h3> One hundred and eighty-five patients had two doses of vaccine administered. The median age at transplant was 63 years. Male comprised 57% of the cohort. IPF was the primary listing diagnosis in 58% of the patients. Twenty patients (10%) developed a de novo DSA or had a rise in their existing antibody titer by more than 50% after the COVID Vaccine. Of these 20 patients, six patients (3.2% of entire cohort) developed de novo DSA. However, this was not statistically significant (McNemar's test, p = 0.288). One patient (0.5%) had considerable graft decline and required AMR treatment, despite which the graft function did not improve and now has chronic lung allograft dysfunction. <h3>Conclusion</h3> In our cohort, twenty patients (10%) developed a de novo DSA or had a rise in their existing antibody titer by more than 50% after the COVID Vaccine. Six patients (3.2% of entire cohort) developed de novo DSA. One patient (0.5%) had considerable graft decline and required AMR treatment. We did not notice a statistically significant de novo DSA development post COVID vaccine.

Utility of Protocol Pancreas Biopsies for De Novo Donor-specific Antibodies.

Utility of Protocol Pancreas Biopsies for De Novo Donor-specific Antibodies.

Clinical Significance of De Novo Donor Specific Antibody Based on the Type of Kidney Transplantation

Preemptive living donor kidney transplantation (P-LDKT) has shown a better prognosis than nonpreemptive living donor KT (NP-LDKT) or deceased donor KT (DDKT). However, association between KT type and de novo donor specific antibody (dnDSA) is uncertain. We retrospectively analyzed 1114 patients who underwent KT between 1994 and 2020. We investigated the clinical significance of dnDSA based on KT type. Mean follow-up duration was 131.5 ± 89.5 months. Mean age of recipients, mismatched number of human leukocyte antigens and incidence of delayed graft function were significantly higher in DDKT group than P-LDKT and NP-LDKT groups. There were no significant differences of incidence of dnDSA and acute rejection within 1 year among them. Death-censored graft survival rate was significantly lower in all groups with dnDSA than without dnDSA, respectively. In positive dnDSA, NP-LDKT and DDKT groups tended to be lower in the death-censored graft survival compared to P-LDKT and there was a significant interaction between type of KT and dnDSA (P = .010). Independent risk factors were acute rejection within 1 year (hazard ratio [HR], 4.341; 95% CI, 1.758-10.720; P = .001), dnDSA positivity (HR, 3.170; 95% CI, 1.364-7.371; P = .007), and eGFR at 12 months after KT (HR, 3.701; 95% CI 2.049-6.686; P < .001). There was no significant difference of incidence of dnDSA based on KT type, but allograft survival was poor in all recipients with dnDSA. NP-LDKT and DDKT with dnDSA showed poor prognosis compared to P-LDKT with dnDSA. Therefore, continuous and rigorous surveillance of DSA needs among NP-LDKT and DDKT.

Evaluation of Cumulative Effect of Standard Triple Immunosuppression on Prevention of De Novo Donor Specific Antibodies (dnDSA) Production in Children after Kidney Transplantation-A Retrospective and Prospective Study.

De novo Donor Specific Antibodies (dnDSA) are associated with inferior graft outcomes. Standard immunosuppression is expected to prevent dnDSA production in low-risk patients. We have evaluated a cumulative effect of a triple immunosuppression (CNI/MMF/Pred), as well as TAC concentration and coefficient of variation on the incidence of dnDSA production. Overall, 67 transplanted patients were evaluated in retrospective (dnDSA for-cause; n = 29) and prospective (dnDSA by protocol; n = 38) groups. In the retrospective group, the eGFR value at first dnDSA detection (median interval—4.0 years post-transplant) was 41 mL/min/1.73 m2; 55% of patients presented biopsy-proven cAMR, and 41% lost the graft within next 2.4 years. Patients from the prospective group presented 97% graft survival and eGFR of 76 mL/min/1.73 m2 at 2 years follow-up, an overall incidence of 21% of dnDSA and 18% of acute (T cell) rejection. None of the patients from the prospective group developed cAMR. Median value of Vasudev score within 2 years of follow-up was not significantly higher in dsDSA negative patients, while median value of TAC C0 > 1–24 months post-transplant was 7.9 in dnDSA negative vs. 7.1 ng/mL in dnDSA positive patients (p = 0.008). Conclusion: dnDSA-negative patients presented a higher exposure to tacrolimus, while not to the combined immunosuppression.