Application of RhD Blood Group to Simulate Antibody Identification Test in Immunohematology Education.

BACKGROUND: Immunohematology skill education is an important part of the transfusion medicine professional training. We tried to solve the difficulty of obtaining suitable and sufficient positive samples in the immunohematology education. METHODS: Different identification panels and panel cells were created by RhD-positive red blood cells (RBCs) and RhD-negative RBCs, according to the underlying antibodies. Diluted anti-D reagent was used as simulated plasma for identification. RESULTS: The antibody identification of single antibody with dose-effect and two antibodies present at the same time were successfully simulated. CONCLUSIONS: It is a practical and cheap method for antibody identification training to use RhD blood group, especially when positive samples are short.

Homozygosity in any HLA locus is a risk factor for specific antibody production: the taboo concept 2.0.

Objective: In a cooperative study of the University Hospital Leipzig, University of Leipzig, and the Charité Berlin on kidney transplant patients, we analysed the occurrence of HLA-specific antibodies with respect to the HLA setup of the patients. We aimed at the definition of specific HLA antigens towards which the patients produced these antibodies. Methods: Patients were typed for the relevant HLA determinants using mainly the next-generation technology. Antibody screening was performed by the state-of-the-art multiplex-based technology using microspheres coupled with the respective HLA alleles of HLA class I and II determinants. Results: Patients homozygous for HLA-A*02, HLA-A*03, HLA-A*24, HLA-B*07, HLA-B*18, HLA-B*35, HLA-B*44, HLA-C*03, HLA-C*04, and HLA-C*07 in the class I group and HLA-DRB1*01, HLA-DRB1*03, HLA-DRB1*07, HLA-DRB1*15, HLA-DQA1*01, HLA-DQA1*05, HLA-DQB1*02, HLA-DQB1*03(7), HLA-DQB1*06, HLA-DPA1*01, and HLA-DPB1*04 in the class II group were found to have a significant higher antibody production compared to the heterozygous ones. In general, all HLA determinants are affected. Remarkably, HLA-A*24 homozygous patients can produce antibodies towards all HLA-A determinants, while HLA-B*18 homozygous ones make antibodies towards all HLA-B and selected HLA-A and C antigens, and are associated with an elevation of HLA-DRB1, parts of DQB1 and DPB1 alleles. Homozygosity for the HLA class II HLA-DRB1*01, and HLA-DRB1*15 seems to increase the risk for antibody responses against most of the HLA class I antigens (HLA-A, HLA-B, and HLA-C) in contrast to HLA-DQB1*03(7) where a lower risk towards few HLA-A and HLA-B alleles is found. The widely observed differential antibody response is therefore to be accounted to the patient's HLA type. Conclusion: Homozygous patients are at risk of producing HLA-specific antibodies hampering the outcome of transplantation. Including this information on the allocation procedure might reduce antibody-mediated immune reactivity and prevent graft loss in a patient at risk, increasing the life span of the transplanted organ.

Post-transplant de novo anti-HLA donor specific antibodies may contribute to poor graft function after haploidentical haematopoietic stem cell transplantation.

De novo anti-HLA donor-specific antibodies (DSAs) were rarely reported in stem cell transplantation patients. We present a case of 39-year-old acute myelogenous leukaemia patient who developed de novo DSAs only 16 days after transplantation with the highest mean fluorescence intensity (MFI) of 7406.23, which were associated with poor graft function (PGF). We used plasma exchange (PE) and intravenous immunoglobulin (IVIg) to reduce DSA level. A series of treatment including mesenchymal stem cells and donor cell transfusion were used to help recover graft function. On day 130, the patient achieved a successful engraftment.

Hexamerization: explaining the original sin of IgG-mediated complement activation in acute lung injury.

Although antibody-mediated lung damage is a major factor in transfusion-related acute lung injury (ALI), autoimmune lung disease (for example, coatomer subunit α [COPA] syndrome), and primary graft dysfunction following lung transplantation, the mechanism by which antigen-antibody complexes activate complement to induce lung damage remains unclear. In this issue of the JCI, Cleary and colleagues utilized several approaches to demonstrate that IgG forms hexamers with MHC class I alloantibodies. This hexamerization served as a key pathophysiological mechanism in alloimmune lung injury models and was mediated through the classical pathway of complement activation. Additionally, the authors provided avenues for exploring therapeutics for this currently hard-to-treat clinical entity that has several etiologies but a potentially focused mechanism.

How anti-c in a D- patient prompted lifesaving work between a transfusion service and a blood center reference laboratory.

This case report showcases an extraordinary collaboration to support the transfusion needs of a patient with a rare phenotype and long-standing anemia due to gastrointestinal bleeding. This report describes the Immunohematology Reference Laboratory testing and logistics of rare blood provision over an 11-year period, as well as a summary of the hematologic, gastroenterologic, and surgical interventions. This case illustrates how a strong collaboration among the clinical team, laboratory, blood center, and the rare donor community facilitated successful management of this patient's anemia until the patient could receive life-changing treatment.

Serologic profiling of D variants in donor routine: unveiling the impact on false-negative results and alloimmunization.

The high number of D variants can lead to the unnecessary use of Rh immune globulin, overuse of D- RBC units, and anti-D allommunization. D variant prevalence varies among ethnic groups, and knowledge of the main variants present in a specific population, their behavior in serologic tests, and their impact on clinical practice is crucial to define the best serologic tests for routine use. The present study aimed to explore the serologic profile of D variants and to determine which variants are most associated with false-negative D typing results and alloimmunization. Donor samples were selected in two study periods. During the first period, D typing was performed on a semi-automated instrument in microplates, and weak D tests were conducted in tube or gel tests. In the second period, D typing was carried out using an automated instrument with microplates, and weak D tests were performed in solid phase. Samples from patients typed as D+ with anti-D were also selected. All samples were characterized by molecular testing. A total of 37 RHD variants were identified. Discrepancies and atypical reactivity without anti-D formation were observed in 83.4 percent of the samples, discrepant D typing results between donations were seen in 12.3 percent, and D+ patients with anti-D comprised 4.3 percent. DAR1.2 was the most prevalent variant. Weak D type 38 was responsible for 75 percent of discrepant samples, followed by weak D type 11, predominantly detected by solid phase. Among the D variants related to alloimmunization, DIVa was the most prevalent, which was not recognized by serologic testing; the same was true for DIIIc. The results highlight the importance of selecting tests for donor screening capable of detecting weak D types 38 and 11, especially in populations where these variants are more prevalent. In pre-transfusion testing, it is crucial that D typing reagents demonstrate weak reactivity with DAR variants; having a serologic strategy to recognize DIVa and DIIIc is also valuable.

A patient with anti-f in India identified by extensive immunohematologic workup.

Anti-f is produced by exposure to the compound antigen ce (f) on red blood cells (RBCs), expressed when both c and e are present on the same protein (cis position). Although anti-f was discovered in 1953, there are few cases reported worldwide because the presence of anti-f is often masked by anti-c or anti-e and is not generally found as a single antibody. In the present case, anti-f was identified by using three-cell screening and 11-cell identification panels. The identification of anti-f was further supported by additional testing, including (1) Rh antigen typing; (2) antibody identification panels (enzyme-treated panel [ficin] and an in-house-constructed Rh panel); (3) look-back and phenotyping of donor RBC units, which were responsible for alloimmunization; and (4) molecular testing of the patient's RBCs.

Complex delayed blood transfusion reaction: A case report.

INTRODUCTION: Inefficient blood transfusions present a significant challenge, leading to the wastage of crucial blood resources and increased medical expenses. This study aims to address this issue by providing a comprehensive analysis of a case involving an ineffective clinical transfusion and outlining the significance of identifying multiple alloantibodies in resolving transfusion challenges. CASE REPORT: We present a detailed follow-up on a patient treatment journey, highlighting the critical role of identifying multiple alloantibodies through various methodologies in addressing the transfusion problem. Subsequently, a strategic intervention was implemented, leading to a successful patient outcome. CONCLUSION: This study underscores the importance of conducting a thorough analysis of ineffective transfusions and implementing scientifically formulated transfusion plans based on rational explanations. Such an approach not only improves hemoglobin levels but also contributes to better patient outcomes, thereby reducing blood resource wastage and medical costs.

Prevalence of Red Blood Cell Alloimmunization Among Pediatric Patients With Sickle Cell Disease in Saudi Arabia.

OBJECTIVE: Sickle cell disease (SCD) is a common hereditary hemoglobin disorder worldwide. One of the main treatments for patients with SCD is the requirement for blood transfusions. Posttransfusion alloimmunization with red blood cell (RBC) antigens continues to be a major risk factor for SCD. The objective of this study was to determine the rate, nature, and risk factors of red cell alloimmunization among pediatric patients with SCD in our center and compare our results with published reports from Saudia Arabia SA, regional countries, and some international countries. MATERIALS AND METHODS: A retrospective chart review of patients with SCD at King Abdulaziz Medical City-Jeddah, between 2008 and 2019 was performed. Demographic characteristics and transfusion histories were recorded. Blood samples were analyzed for alloimmunization using immunohematologic techniques. RESULTS: In total, 121 patients were analyzed. Alloantibodies were detected in 21 patients (17.4%) and were mostly single in 15 patients (71.4%), anti-K (23.7%), anti-E (19.0%), and anti-S (9.5%). The other 6 patients (28.6%) had multiple alloantibodies, especially the combination of anti-C and anti-K (9.5%) and the combination of anti-C and anti-E (9.5%). Alloantibody levels were significantly higher in patients with frequent hospital admissions (>5 times annually), those who had an exchange blood transfusion, those younger than 3 years old, and those who received a larger number of blood units ( P ≤0.05). CONCLUSION: The rate of RBC alloimmunization is determined and considered relatively low compared with that in other nations. Matching for extended RBC antigens to include ABO, RH (D, C, c, E, e), K, Fy a , Fy b , Jk a , and Jk b antigens in the screening panel for donors and recipients is highly recommended to ensure better transfusion practices and avoid transfusion-related complications.

A personalised delisting strategy enables successful kidney transplantation in highly sensitised patients with preformed donor-specific anti HLA antibodies.

This study investigates kidney transplant outcomes in highly sensitised patients after implementing a delisting strategy aimed at enabling transplantation despite preformed donor-specific antibodies (preDSA), with the goal of reducing acute antibody-mediated rejection (aAMR) risk. Fifty-three sensitised recipients underwent kidney transplant after delisting prohibited HLA antigens, focusing initially in low MFI antibodies (<5000), except for anti-HLA-DQ. If insufficient, higher MFI antibodies were permitted, especially for those without an immunogenic eplet pattern assigned. Delisting of Complement-fixing antibodies (C1q+) was consistently avoided. Comparison cohorts included 53 sensitised recipients without DSA (SwoDSA) and 53 non-sensitised (NS). The average waiting time prior to delisting was 4.4 ± 1.8 years, with a reduction in cPRA from 99.7 ± 0.5 to 98.1 ± 0.7, followed by transplantation within 7.2 ± 8.0 months (analysed in 34 patients). Rejection rates were similar among preDSA, SwoDSA, and NS groups (16%, 8%, and 11%, respectively; p = 0.46). However, aAMR was higher in the preDSA group (12%, 4%, and 2%, respectively; p = 0.073), only presented in recipients with DSA of MFI >5000. The highest MFI DSA were against HLA-DP (Median: 10796 MFI), with 50% of preDSA aAMR cases due to anti-DP antibodies (n = 3). Graft survival rates at 1 and 5 years in preDSA group were 94%, and 67%, comparable to SwoDSA (94%, and 70%; p = 0.69), being significantly higher in the NS group (p = 0.002). The five-year recipient survival rate was 89%, comparable to SwoDSA and NS groups (p = 0.79). A delisting strategy enables safe kidney transplant in highly sensitised patients with preDSA, with a slight increase in aAMR and comparable graft and patient survivals to non-DSA cohorts.

Sensitive HLA antibody testing and the risk of antibody-mediated rejection and graft failure.

Solid phase detection and identification of HLA antibodies in kidney transplantation currently relies on single antigen bead (Luminex®) assays, which is more sensitive than the previously used enzyme-linked immunosorbent assays (ELISA). To evaluate the impact of more sensitive HLA testing on antibody-mediated rejection (AMR) occurrence and allograft survival, we analysed 1818 renal allograft recipients transplanted between March 2004 and May 2021. In 2008, solid phase testing switched from ELISA to Luminex. We included 393 (21.6%) transplantations before and 1425 (78.4%) transplantations after transition from ELISA- to Luminex-based testing. For this study, bio-banked ELISA era samples were tested retrospectively with Luminex. Significantly less pretransplant DSA were found in patients transplanted with pre-existing HLA antibodies in the Luminex (109/387) versus the ELISA period (43/90) (28% vs. 48%, p < 0.01). Throughout histological follow-up, 169 of 1818 (9.3%) patients developed AMR. After implementing Luminex-based testing, the rate of AMR significantly decreased (p = 0.003). However, incidence of graft failure did not significantly differ between both eras. In conclusion, less patients with pretransplant DSA were transplanted since the implementation of Luminex HLA testing. Transition from ELISA- to Luminex-based HLA testing was associated with a significant decrease in AMR occurrence post-transplantation. Since the decline of AMR did not translate into improved graft survival, Luminex-based testing has the added value of preventing low-risk AMR cases. Therefore, Luminex' high sensitivity must be balanced against waiting time for a suitable organ.

Successful management of maternal anti-PP1Pk alloimmunization in pregnancy with therapeutic plasma exchange and intravenous immunoglobulin.

Anti-PP1PK alloimmunization is rare given ubiquitous P1PK expression. Prevention of recurrent miscarriages and hemolytic disease of the fetus and newborn (HDFN) in pregnant individuals with anti-PP1PK antibodies has relied upon individual reports. Here, we demonstrate the successful management of maternal anti-PP1PK alloimmunization in a 23-year-old, G2P0010, with therapeutic plasma exchange (TPE), intravenous immunoglobulin (IVIG), and monitoring of anti-PP1Pk titers. Twice-weekly TPE (1.5 plasma volume [PV], 5% albumin replacement) with weekly titers and IVIG (1 g/kg) was initiated at 9 weeks of gestation (WG). The threshold titer was ≥16. Weekly middle cerebral artery-peak systolic velocities (MCA-PSV) for fetal anemia monitoring was initiated at 16 WG. PVs were adjusted throughout pregnancy based on treatment schedule, titers, and available albumin. Antigen-negative, ABO-compatible RBCs were obtained through the rare donor program and directed donation. An autologous blood autotransfusion system was reserved for delivery. Titers decreased from 128 to 8 by 10 WG. MCA-PSV remained stable. At 24 WG, TPE decreased to once weekly. After titers increased to 32, twice-weekly TPE resumed at 27 WG. Induction of labor was scheduled at 38 WG. Vaginal delivery of a 2950 g neonate (APGAR score: 9, 9) occurred without complication (Cord blood: 1+ IgG DAT; Anti-PP1Pk eluted). Newborn hemoglobin and bilirubin were unremarkable. Discharge occurred postpartum day 2. Anti-PP1Pk alloimmunization is rare but associated with recurrent miscarriages and HDFN. With multidisciplinary care, a successful pregnancy is possible with IVIG and TPE adjusted to PV and titers. We also propose a patient registry and comprehensive management plan.

Sequential administration of anti-complement component C5 eculizumab and type-2 anti-CD20 obinutuzumab for the treatment of early antibody-mediated rejection after kidney transplantation: A proof of concept.

Kidney transplant (KT) candidates with donor-specific antibodies (DSA) exhibit exceedingly high antibody-mediated rejection (ABMR) and allograft loss rates. Currently, treatment of ABMR remains an unmet clinical need. We report the use of the anti-C5 eculizumab and the type-2 anti-CD20 obinutuzumab in two patients with early ABMR. Eculizumab (900 mg IV) led to complete inhibition of the terminal complement cascade (unremarkable AP50 and CH50 activity) and prompt stoppage of complement-dependent antibody-mediated allograft injury (clearance of intra-graft C4d and C5b-9 deposition). Despite complement inhibition, obinutuzumab (1000 mg IV) determined full and long-lasting peripheral B-cell depletion, with significant reduction in all DSA. Graft function improved, remaining stable up to three years of follow-up. No signs of active ABMR and rebound DSA were detected. Obinutuzumab B-cell depletion and inhibition of DSA production were not affected by complement blockage. Further studies are needed to confirm the potential benefit of obinutuzumab in association with complement inhibitors.

Bortezomib for antibody-mediated rejection of kidney transplant in youth: Associations with donor-specific antibody.

BACKGROUND: Antibody-mediated rejection is one of the most significant risk factors for allograft dysfunction and failure in children and adolescents with kidney transplants, yet optimal treatment remains unidentified. To date, there are mixed findings regarding the use of Bortezomib, a plasma cell apoptosis inducer, as an adjunct therapy in the treatment of antibody-mediated rejection. METHODS: In a retrospective single center study, we reviewed the efficacy and tolerability of bortezomib as adjunct therapy for treatment-refractory antibody-mediated rejection. RESULTS: Six patients with a median age of 14.6 years (range 6.9-20.1 years) received bortezomib at a mean of 71 months (range 15-83 months) post-kidney transplant. Four patients experienced decline in estimated glomerular filtration rate (eGFR) from 4% to 42%. One patient started bortezomib while on hemodialysis and did not recover graft function, and another patient progressed to hemodialysis 6 months after receiving bortezomib. Although DSA did not completely resolve, there was a statistically significant decline in DSA MFI pre and 12-months post-BZ (p = .012, paired t-test) for the subjects who were not on dialysis at the time of bortezomib. Chronic Allograft Damage Index (CADI) score of ≥3 was seen in all six subjects at their biopsy prior to therapy. No adverse effects were reported. CONCLUSIONS: Bortezomib was well tolerated and resulted in improvements in MFI of DSA among four pediatric subjects without allograft failure, although no effects were observed on eGFR trajectory. Further studies are needed to clarify whether earlier intervention with bortezomib could prevent renal failure progression.

Kidney transplant candidates' perspectives on the implementation of a Canadian Willingness to Cross program: A strategy to increase access to kidney transplantation for highly sensitized patients.

BACKGROUND: Kidney transplantation is the optimal treatment for end-stage renal disease. However, highly sensitized patients (HSPs) have reduced access to transplantation, leading to increased morbidity and mortality on the waiting list. The Canadian Willingness to Cross (WTC) program proposes allowing transplantation across preformed donor specific antibodies (DSA) determined to be at a low risk of rejection under the adaptive design framework. This study collected patients' perspectives on the development of this program. METHODS: Forty-one individual interviews were conducted with kidney transplant candidates from three Canadian transplant centers in 2022. The interviews were digitally recorded and transcribed for subsequent analyses. RESULTS: Despite limited familiarity with the adaptive design, participants demonstrated trust in the researchers. They perceived the WTC program as a pathway for HSPs to access transplantation while mitigating transplant-related risks. HSPs saw the WTC program as a source of hope and an opportunity to leave dialysis, despite acknowledging inherent uncertainties. Some non-HSPs expressed concerns about fairness, anticipating increased waiting times and potential compromise in kidney graft longevity due to higher rejection risks. Participants recommended essential strategies for implementing the WTC program, including organizing informational meetings and highlighting the necessity for psychosocial support. CONCLUSION: The WTC program emerges as a promising strategy to enhance HSPs' access to kidney transplantation. While HSPs perceived this program as a source of hope, non-HSPs voiced concerns about distributive justice issues. These results will help develop a WTC program that is ethically sound for transplant candidates.

Bridge-to-transplant temporary mechanical circulatory support and risk of allosensitization.

INTRODUCTION: Since the 2018 change in the US adult heart allocation policy, more patients are bridged-to-transplant on temporary mechanical circulatory support (tMCS). Previous studies indicate that durable left ventricular assist devices (LVAD) may lead to allosensitization. The goal of this study was to assess whether tMCS implantation is associated with changes in sensitization. METHODS: We included patients evaluated for heart transplants between 2015 and 2022 who had alloantibody measured before and after MCS implantation. Allosensitization was defined as development of new alloantibodies after tMCS implant. RESULTS: A total of 41 patients received tMCS before transplant. Nine (22.0%) patients developed alloantibodies following tMCS implantation: 3 (12.0%) in the intra-aortic balloon pump group (n = 25), 2 (28.6%) in the microaxial percutaneous LVAD group (n = 7), and 4 (44.4%) in the veno-arterial extra-corporeal membrane oxygenation group (n = 9)-p = .039. Sensitized patients were younger (44.7 ± 11.6 years vs. 54.3 ± 12.5 years, p = .044), were more likely to be sensitized at baseline - 3 of 9 (33.3%) compared to 2 out of 32 (6.3%) (p = .028) and received more transfusions with red blood cells (6 (66.6%) vs. 8 (25%), p = .02) and platelets (6 (66.6%) vs. 5 (15.6%), p = .002). There was no significant difference in tMCS median duration of support (4 [3,15] days vs. 8.5 [5,14.5] days, p = .57). Importantly, out of the 11 patients who received a durable LVAD after tMCS, 5 (45.5%) became sensitized, compared to 4 out of 30 patients (13.3%) who only had tMCS-p = .028. CONCLUSIONS: Our findings suggest that patients bridged-to-transplant with tMCS, without significant blood product transfusions and a subsequent durable LVAD implant, have a low risk of allosensitization. Further studies are needed to confirm our findings and determine whether risk of sensitization varies by type of tMCS and duration of support.

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.

Association of HLA B- and T-cell molecular mismatches with HLA antibodies, rejection, and graft survival in pediatric kidney transplantation.

BACKGROUND: Optimizing graft survival and diminishing human leukocyte antigen (HLA) sensitization are essential for pediatric kidney transplant recipients. More precise HLA matching predicting epitope mismatches could reduce alloreactivity. We investigated the association of predicted HLA B- and T-cell molecular mismatches with the formation of de novo donor-specific antibodies, HLA antibodies, rejection, and graft survival. METHODS: Forty-nine pediatric kidney transplant recipients transplanted from 2009 to 2020 were retrospectively studied. Donors and recipients were high-resolution HLA typed, and recipients were screened for HLA antibodies posttransplant. HLA-EMMA (HLA Epitope MisMatch Algorithm) and PIRCHE-II (Predicted Indirectly ReCognizable HLA Epitopes) predicted the molecular mismatches. The association of molecular mismatches and the end-points was explored with logistic regression. RESULTS: Five recipients (11%) developed de novo donor-specific antibodies. All five had de novo donor-specific antibodies against HLA class II, with four having HLA-DQ antibodies. We found no associations between PIRCHE-II or HLA-EMMA with de novo donor-specific antibodies, HLA sensitization, graft loss, or rejection. However, we did see a tendency towards an increased odds ratio in PIRCHE-II predicting de novo donor-specific antibodies formation, with an odds ratio of 1.12 (95% CI: 0.99; 1.28) on HLA class II. CONCLUSION: While the study revealed no significant associations between the number of molecular mismatches and outcomes, a notable trend was observed - indicating a reduced risk of dnDSA formation with improved molecular match. It is important to acknowledge, however, that the modest population size and limited observed outcomes preclude us from making definitive conclusions.

Repeated human leukocyte antigens eplets, importance of typing the partner.

INTRODUCTION: Antibody-mediated rejection (AMR) is the most common cause of immune-mediated allograft failure after kidney transplant and impacts allograft survival. Previous sensitization is a major risk factor for development of donor specific antibodies (DSA). AMR can have a wide range of clinical features such as impaired kidney function, proteinuria/hypertension or can be subclinical. HLA molecules have specific regions of antigens binding antibodies called epitopes and eplets are considered essential components responsible for immune recognition. We present a patient with subclinical AMR 1 week post transplantation. CASE REPORT: A 48-year-old, caucasian woman with end-stage kidney disease (ESKD) secondary to autosomal dominant polycystic kidney disease (ADPKD) on peritoneal dialysis was registered in deceased donor waitlist. She was a hypersensitized patient from 3 prior pregnancies with a calculated panel reactive antibody of 93,48%. She was transplanted through kidney paired exchange donation with no evidence of DSA pre transplantation. Surgery and post-op were unremarkable with excellent and immediate graft function. Per protocol DSA levels on the 5th day was DR1 of 3300 MFI, with an increase in MFI by day 13 with 7820 MFI and a new B41 1979MFI. Allograft kidney biopsy findings were diagnostic of AMR and she was treated with immunoglobulin and plasmapheresis. As early onset AMR post transplantation was observed an anamnestic response was hypothesized from a previous exposure to allo-HLA. We decided to type her husband, her son's father, which was presented with DSA. Mismatch eplet analysis revealed a shared 41 T and 67LQ eplets between the donor and husband, responsible for the reactivity and new HLA class I B41 and HLA class II DR1 DSA, respectively. DISCUSSION: Shared eplets between the patient husband and donor was responsible for the alloimmune response and early development of DSAs. This case highlights the importance of early monitoring DSA levels in highly sensitized patients after transplant in order to promptly address and lower inflammatory damage. Mismatch eplet analysis can provide a thorough and precise evaluation of immune compatibility providing a useful technique to immune risk stratification, donor selection and post-transplant immunosuppressive therapy and monitoring.

Late graft failure of pig-to-rhesus renal xenografts has features of glomerulopathy and recipients have anti-swine leukocyte antigen class I and class II antibodies.

Prolonged survival in preclinical renal xenotransplantation demonstrates that early antibody mediated rejection (AMR) can be overcome. It is now critical to evaluate and understand the pathobiology of late graft failure and devise new means to improve post xenograft outcomes. In renal allotransplantation the most common cause of late renal graft failure is transplant glomerulopathy-largely due to anti-donor MHC antibodies, particularly anti-HLA DQ antibodies. We evaluated the pig renal xenograft pathology of four long-surviving (>300 days) rhesus monkeys. We also evaluated the terminal serum for the presence of anti-SLA class I and specifically anti-SLA DQ antibodies. All four recipients had transplant glomerulopathy and expressed anti-SLA DQ antibodies. In one recipient tested for anti-SLA I antibodies, the recipient had antibodies specifically reacting with two of three SLA I alleles tested. These results suggest that similar to allotransplantation, anti-MHC antibodies, particularly anti-SLA DQ, may be a barrier to improved long-term xenograft outcomes.