Novo 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.

Early CYP3A5 Genotype-Based Adjustment of Tacrolimus Dosage Reduces Risk of De Novo Donor-Specific HLA Antibodies and Rejection among CYP3A5-Expressing Renal Transplant Patients.

Our previous retrospective single-center cohort study found, at 3-year follow-up, a trend toward low tacrolimus trough levels and an increased risk of de novo donor-specific anti-HLA antibodies (DSAs) and of antibody-mediated rejection (ABMR) in CYP3A5-expressing patients. Determining CYP3A5-expression status immediately after renal transplant would allow early genotype-based dosage adjustment of tacrolimus and might prevent the occurrence of de novo DSAs and ABMR, improving transplant outcome. 160 renal allograft recipients who underwent renal transplant at the University Hospital Essen between May 2019 and May 2022 were genotyped for the CYP3A5 rs776746 polymorphism within the first two weeks after transplant, and genotype-based dose adjustment of tacrolimus was performed for the follow-up of 2 years. CYP3A5 expression was detected in 33 (21%) of the 160 patients. Tacrolimus trough levels were similar in CYP3A5 expressers and nonexpressers over the entire 2-year follow-up period. However, we observed a trend toward slightly higher tacrolimus trough levels in CYP3A5 expressers, who, as expected, required tacrolimus dosages twice as high as did nonexpressers during follow-up. Calcineurin inhibitor (CNI) nephrotoxicity-free survival rates were comparable between CYP3A5 expressers and nonexpressers (p = 0.49). Rejection-free survival rates (p = 0.89), de novo anti-HLA antibody-free survival rates (p = 0.57) and de novo DSA-free survival rates (p = 0.61) did not differ between the two groups. Early detection of CYP3A5-expression status and resultant genotype-based adjustment of tacrolimus dosage after renal transplant protected patients from transplant rejection and de novo DSA formation and was not associated with increased incidence of CNI toxicity among CYP3A5 expressers.

C1q-Fixing De Novo Donor Specific Antibodies in Therapeutic Management of Chronic Antibody-Mediated Rejection Postkidney Transplantation

Evidence for C1q-fixing donor-specific antibodies (DSA) after chronic antibody-mediated rejection (CABMR) treatment is lacking. We investigated if C1q-DSA could predict therapy response in patients with biopsy-proven CABMR. Twenty kidney transplant patients with late-onset DSA were enrolled. Patients with biopsy-proven CABMR received three plasma pheresis sessions, one dose of rituximab (375 mg/m2), and steroid pulse therapy. We monitored IgG-DSA, C1q-DSA, and renal graft function for >2 years post-CABMR treatment. Patients with C1q-DSA mean fluorescence intensity (MFI) decreased by less than 50% post-treatment were classified as C1q-nonresponders. We compared Banff classification scores (g, ptc, cg, c4d) before and 6 months after treatment. Fourteen (70%) of 20 patients were C1q-DSA positive. The MFIs of IgG-DSA and C1q-DSA before treatment were significantly higher in the C1q-DSA positive group than in the negative group, at 20,035 and 10,918 (P = .008) and 17,702 and 21 (P < .001), respectively. Fifteen patients (75%) were diagnosed with CABMR via biopsy, and 12 patients received rejection therapy. Five (41.7%) patients were C1q-responders and seven (58.3%) were C1q-nonresponders. The MFIs of C1q-DSA before treatment were not significantly different between the two groups (11,521 vs. 13,985). Renal graft function was stable after treatment in C1q-responders for 3 years. In contrast, renal graft function tended to deteriorate in C1q-nonresponders. Biopsy showed improvement in scores in 75% of C1q-responders while deterioration in scores in 42.9% of C1q-nonresponders. C1q-DSA may be a good predictor of outcomes after CABMR treatment.

Risk HLA-DQ Heterodimer Mismatch Is Associated with De Novo Donor-Specific Antibodies in Pediatric Kidney Transplant Recipients

Risk HLA-DQ Heterodimer Mismatch Is Associated with De Novo Donor-Specific Antibodies in Pediatric Kidney Transplant Recipients

HLA Mismatches Identified by a Novel Algorithm Predict Risk of Antibody-mediated Rejection From De Novo Donor-specific Antibodies.

The development of de novo donor-specific antibodies (dnDSA) and antibody-mediated rejection (AMR) remains a barrier to long-term graft and patient survival. Most dnDSA are directed against mismatched donor HLA-DQ antigens. Here, we describe a novel algorithm, which we have termed categorical amino acid mismatched epitope, to evaluate HLA-DQ mismatches. In this algorithm, amino acid residues of HLA-DQ protein were categorized into 4 groups based on their chemical characteristics. The likelihood of categorically mismatched peptides presented by the recipient's HLA-DRB1 was expressed as a normalized value, %Rank score. Categorical HLA-DQ mismatches were analyzed in 386 heart transplant recipients who were mismatched with their donors at the HLA-DQB1 locus. We found that the presence of DQB1 mismatches with %Rank score ≤1 was associated with the development of dnDSA (P = 0.002). Furthermore, dnDSA increased the risk of AMR only in recipients who had DQ mismatches with %Rank score ≤1 (hazard ratio = 5.8), but the freedom from AMR was comparable between recipients with dnDSA and those without dnDSA if %Rank scores of DQ mismatching were >1. These results suggest that HLA-DQ mismatches evaluated by the categorical amino acid mismatched epitope algorithm can stratify the risk of development of dnDSA and AMR in heart transplant recipients.

(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.