Positive Crossmatch Research Articles

Outcomes after intestinal re-transplant: A detailed, single-center analysis of clinical and technical factors

BackgroundIntestinal transplantation (ITx) has evolved into a viable option for patients suffering from intestinal failure (IF). As graft and patient survival increase, we enter a new era where re-transplantation (re-ITx) is increasingly considered. Re-ITx grafts historically are less successful than their primary counterpart. While re-ITx is challenging for the obvious reasons of a re-do operation, there are potentially modifiable pre-transplant clinical and technical factors which are not yet understood. MethodsWe conducted an in-depth review of our re-ITx experience at a high volume transplant center, and describe unique predictors associated with improved outcomes. ResultsThere were 132 primary ITx performed from 1991-2021; 44 primary ITx failed (33%) and of those, 25 (56%) were re-transplanted within the time of this retrospective review. The median time to re-ITx was 13 months (5 days–6 years). I-ITx recipients were more commonly re-transplanted with liver-inclusive grafts (64%). Re-ITx recipients were more often male (p=0.05), had positive crossmatch (p=0.01), PRA>20% (p=0.03), and underwent ATG-induction (p=0.00). The mean graft survival in months in primary ITx was 74.0 (0.0 - 303.2) and in re-ITx was 60.0 (0.0 - 155.83) (p=0.37). The leading indication for re-ITx was ACR of the primary graft (64%). Successful re-ITx (graft survival >1 year) was significantly associated with ATG-induction (p=0.003). Liver-inclusive grafts demonstrated increased 1-year survival compared with liver-free grafts, but not significantly (primary ITx: 72% vs 55%; re-ITx: 75% vs 57%). Enterectomy of the primary graft prior to re-ITx appeared to increase overall graft survival after re-ITx, but not significantly (70 vs 40 months, p=0.17). Enterocolonic continuity was associated with overall longer graft survival after re-ITx (95 vs 40 months, p=0.03). ConclusionWe demonstrate several factors to consider when evaluating patients for re-ITx, a multicenter study is needed to understand how patient selection, clinical management, and technical modifications can improve outcomes after re-ITx.

Impacts of Pre-transplant Panel-Reactive Antibody on Post-transplantation Outcomes: A Study of Nationwide Heart Transplant Registry Data.

The number of sensitized heart failure patients on waiting lists for heart transplantation (HTx) is increasing. Using the Korean Organ Transplantation Registry (KOTRY), a nationwide multicenter database, we investigated the prevalence and clinical impact of calculated panel-reactive antibody (cPRA) in patients undergoing HTx. We retrospectively reviewed 813 patients who underwent HTx between 2014 and 2021. Patients were grouped according to peak PRA level as group A: patients with cPRA ≤10% (n= 492); group B: patients with cPRA >10%, <50% (n=160); group C patients with cPRA ≥50% (n=161). Post-HTx outcomes were freedom from antibody-mediated rejection (AMR), acute cellular rejection, coronary allograft vasculopathy, and all-cause mortality. The median follow-up duration was 44 (19-72) months. Female sex, re-transplantation, and pre-HTx renal replacement therapy were independently associated with an increased risk of sensitization (cPRA ≥50%). Group C patients were more likely to have longer hospital stays and to use anti-thymocyte globulin as an induction agent compared to groups A and B. Significantly more patients in group C had positive flow cytometric crossmatch and had a higher incidence of preformed donor-specific antibody (DSA) compared to groups A and B. During follow-up, group C had a significantly higher rate of AMR, but the overall survival rate was comparable to that of groups A and B. In a subgroup analysis of group C, post-transplant survival was comparable despite higher preformed DSA in a desensitized group compared to the non-desensitized group. Patients with cPRA ≥50% had significantly higher incidence of preformed DSA and lower freedom from AMR, but post-HTx survival rates were similar to those with cPRA <50%. Our findings suggest that sensitized patients can attain comparable post-transplant survival to non-sensitized patients when treated with optimal desensitization treatment and therapeutic intervention.

International Kidney Paired Donation – The Experience of a Single Center

Introduction: Kidney transplantation is the preferred treatment for end-stage renal disease, but organ scarcity can result in long waiting times. Living-donor kidney transplantation offers an alternative to deceased donation, but HLA or AB0 incompatibility can pose a significant obstacle. This study aimed to show the results achieved by a portuguese hospital since its integration into an international cross-over program, the South Alliance for Transplants (SAT). Methods: The SAT program was founded in 2017 and is composed of ten Spanish hospitals, three Italian hospitals and one Portuguese hospital. The program runs every 4 months and enrolled only pairs that were incompatible. Organ transportation is carried out in partnership with the Portuguese Air Force. Results: Three distinct cross-over kidney transplants were performed in partnership with three Spanish hospitals, culminating in the transplantation of three Portuguese patients out of a total of seven patients. The first swap was performed in March 2020, at the beginning of the COVID-19 pandemic, in partnership with two Portuguese and one Spanish hospital. It involved one donor/recipient pair from each country, with AB0 incompatibility between the Portuguese donor and recipient, and no complications were reported. The second swap occurred in December 2021, with three donor/recipient pairs (one Portuguese, where the recipient presented anti-donor antibodies and positive crossmatch with the potential donor, and two from two Spanish hospitals). It was complicated by type-IB cellular rejection in the Portuguese recipient, one week after transplantation, which was treated with corticosteroid therapy. The third swap, also in December 2021, involved two donor/recipient pairs (one Portuguese and one Spanish). It was complicated by delayed renal function due to acute tubular necrosis (histological diagnosis) in the Portuguese recipient. At follow-up, the patients‘ serum creatinine levels were within normal limits, and no other unexpected outcomes were recorded. Conclusion: SAT program has allowed some successful cross-over kidney transplants, probably improving the outcomes of kidney transplantation in Portugal. The expansion of such programs may contribute to a more efficient use of the available resources, increasing the number of transplants performed and reducing waiting times

Abstract 16051: Heart Transplantation With a Positive Crossmatch in Pediatric Recipients is Associated With Increased Mortality in the Current Era: An Analysis of the United Network for Organ Sharing Database

Introduction: Congenital heart disease (CHD) patients undergoing heart transplantation (HT) often have anti-HLA antibodies (sensitization), increasing the likelihood of a positive crossmatch and in turn an increased risk of mortality post-HT. The burden of sensitization in pediatric HT recipients and outcomes in such patients in the current era are unknown. Methods: The United Network for Organ Sharing (UNOS) database was queried for patients &lt;18 y/o with CHD undergoing HT between 4/1/2015 and 12/31/2019. Panel reactive antibody (PRA) at HT was collected; patients were grouped into 3 categories: nonsensitized (PRA &lt;10%), moderately sensitized (PRA 10-79%), and highly sensitized (PRA ≥80%). Data regarding crossmatch at HT were collected. One-year post-HT mortality based on sensitization category and crossmatch result were evaluated using multivariable Cox regression. Results: During the study period, 881 CHD patients with PRA data underwent HT; 69% nonsensitized, 22% moderately sensitized, and 9% highly sensitized. Positive crossmatch by flow cytometry or cytotoxicity was more commonly seen in highly sensitized patients (Table 1). Highly sensitized patients had 28% 1-year mortality. After adjustment, both 1-year mortality and graft loss were higher in highly sensitized patients than nonsensitized patients (HR 4, CI 2.4-6.7, P&lt;0.001 and HR 6.8, CI 3.6-12.8, P&lt;0.001, respectively); positive crossmatch by flow cytometry or cytotoxicity was also associated with increased risk of mortality and graft loss (HR 2.1, CI 1.3-3.4, P = 0.002 and HR 3.1, CI 1.7-5.6, P&lt;0.001, respectively). Conclusions: Highly sensitized pediatric CHD patients have 1-year post-HT mortality of nearly 30%, a 4-fold increase compared to nonsensitized patients; positive crossmatch also increased the risk of mortality and graft loss. Due to these poor outcomes, aggressive desensitization as well as alternatives to transplant should be considered in these high-risk patients.

Red cell antibodies or noise? A case series on reactivity against the ingredients in column matrix

Abstract Noise in the immunohematological investigations can be described as a false reactivity of red blood cells (RBCs) in serologic testing that is not related to the interaction of RBC antigens and antibodies that the test system is intended to detect. These false-positive reactions can cause confusion during the cross-matching and RBC antibody screening and may result in delays in patient transfusion. Although these antibodies are predominantly clinically insignificant, proper laboratory work-up is indicated to avoid misidentification of a clinically significant antibody as a noise. In this report, we describe the three rare cases where the reactivity was found against the ingredients of the column matrix (glass beads). It is imperative that such reactivity is recognized and resolved during the investigation of blood group discrepancies, positive RBC antibody screens and in cases of positive cross-matches.

Deciphering the True Immunologic Risk in Renal Transplantation in Patients With HIV

Since 1995, rates of end-stage renal disease have risen dramatically in patients living with HIV infection. However, given the concern for higher rates of acute rejection in this patient population, the immunologic threat posed by HIV infection is a specter clinicians must continually confront. Living donor transplantation may negate this risk; this study aims to assess the benefit of living donor transplantation in this population and to ascertain the immunologic risk faced by patients who are HIV-infected. The 2021 UNOS database was queried, and all HIV-infected kidney transplant recipients since 1987 were identified. Recipients were stratified based on deceased (DDKT) vs living (LDKT) donor status. Overall survival, allograft survival, acute rejection, panel reactive antibody (PRA) percentage, and crossmatch positivity were compared between groups. One thousand two hundred twenty-six patients underwent DDKT, and 304 patients underwent LDKT. Living donor kidney transplantation demonstrated greater overall survival (P=.045) and graft survival (P < .001). However, no difference in acute rejection was noted between the cohorts, and no difference in overall or graft survival was evident based on PRA percentage. Crossmatch positive status did not negatively affect graft survival. Patients with HIV undergoing LDKT fared better than those undergoing DDKT. Nevertheless, patients at higher immunologic risk-elevated PRA% and crossmatch positivity-did not experience graft loss at a higher rate than patients at lower immunologic risk. These results were valid in both DDKT and LDKT cohorts. These findings suggest that infection with HIV does not overtly increase patients' immunologic risk, and concerns surrounding transplantation in this population may be overestimated.

SAT239 Deceased Donor Parathyroid Allotransplant For Sever Refractory Iatrogenic Hypoparathyroidism

Abstract Disclosure: K.M. Devon: None. A. Zahedi: None. A. Madani: None. J.D. Pasternak: None. B. Saravana-Bawan: None. A. Humar: None. T. Kathryn: None. While Halstead experimented with dog parathyroid transplantation, the first reported human parathyroid allotransplant appeared in the Annals of Surgery in 1911. Efforts of varying success in restoring calcium homeostasis in patients with refractory hypoparathyroidism after thyroidectomy have included parathyroid transplantation(tx), mainly in immunosuppressed kidney transplant recipients, using cryopreserved, cultured, or hypercellular tissues. Recently, cases of living-donor parathyroid allotransplants have been reported. We present a 46 year-old woman who developed hypoparathyroidism following total thyroidectomy 9 years prior. Treatment included two years of continuous teriparatide via CAD pump. Complications of portacath sepsis and pulmonary emboli, required intensive care. At the time of transplantation, our patient was taking elemental calcium 16 grams daily, magnesium 12 grams daily, calcitriol 8 ug daily, hydroochlorothiazide 25 mg twice daily, and nonetheless requiring biweekly intravenous calcium for symptoms and Calcium levels of 1.6 mmol/l (2.2-2.6 mmol/L). PTH ranged between 0.6- 1.2 pmol/l with poor quality of life. A medically suitable neurologically deceased donor was identified through the provincial organ donation organization. Her cumulative cPRA was 98% (Class I-95%/II-81%). Virtual crossmatch only positive for DQ2 specificity with weak positive B-cell flow crossmatch. Four healthy parathyroids were retrieved. The tissue was minced and placed into pockets in the recipient’s right brachioradialis muscle, under local anaesthesia with sedation. Ischemic time was 2.5 hours. She was induced with basiliximab and received tacrolimus, mycophenolate, and prednisone as immunotherapy. Evidence of biochemical parathyroid function was present post-tx day 9, and she was weaned off all calcium homeostatic medications by day 35, remaining asymptomatic at 7 months at the time of writing, with no calcium infusions. Self-reported quality of life is significantly improved. PTH 0.8-2.8 pmol/L and Calcium 2.06-2.37 mmol/l. To our knowledge this is the first successful fresh normal tissue deceased donor parathyroid transplant in a non-transplant recipient in North America. One study suggests that despite immunosuppression risks, 14 percent of patients would entertain parathyroid allotransplantation. We are currently recruiting additional patients with the aim of demonstrating that deceased donor parathyroid allotransplant using fresh tissue and immunosuppression is a novel viable and curative approach to treat permanent severe hypoparathyroidism. Presentation: Saturday, June 17, 2023

Testing re-optimisation strategies in international kidney exchange programmes by the ENCKEP simulator

We tested re-optimisation strategies for international kidney exchange programmes using the simulator developed by the ENCKEP COST Action. Kidney exchange programmes (KEPs) are operating in most of the European countries to facilitate the exchange of kidney donors for the recipients with incompatible living donors. The optimal solutions for national and international KEPs are typically selected in every three months based on the compatibilities estimated on the individual immunological data. However, these estimations are not always accurate, and if a positive crossmatch is found in the laboratory crossmatch tests then the corresponding exchange cycle (or chain) must be cancelled. Depending on the matching process, the coordinators may use different re-optimisation strategies to repair the failed solutions. We examine the effects of using multiple rounds of re-optimisation with different optimisation strategies, such as fixing good cycles in the intermediate solutions or prioritising transplants with negative crossmatch tests in previous rounds. In the context of international KEPs we also consider the possibility of testing and prioritising national transplants in the solutions. We measure the performance of these policies regarding the number of transplants and the number of compatibility tests conducted in a time period. By extending our results presented in [16], we performed simulations for a large number of instances to measure the effects of various re-optimisation policies. Our main findings show a clear trade-off in the number of transplants versus the number of tests and re-optimisation rounds.

P100 HLA-Cw epitope analysis can resolve positive physical flow cytometry crossmatch in absence of donor-specific antibodies and prozone effect – A case study

P100 HLA-Cw epitope analysis can resolve positive physical flow cytometry crossmatch in absence of donor-specific antibodies and prozone effect – A case study

P703 Impact of a positive crossmatch with negative donor specific antibody on kidney transplantation

P703 Impact of a positive crossmatch with negative donor specific antibody on kidney transplantation

Living Donor Liver Transplantation in Patients with Preformed Donor-Specific Anti-Human Leukocyte Antigen Antibodies Using Preoperative Desensitization Therapy According to Intensity of Donor-Specific Antibodies: A Single-Center Study.

BACKGROUND In liver transplantation (LT), preoperative desensitization therapy is considered necessary in patients positive for donor-specific anti-human leukocyte antigen antibodies (DSAs). However, the relationship between DSA intensity and the necessary desensitization therapy is unclear. MATERIAL AND METHODS A total of 37 adult living donor (LD) LTs performed between January 2016 and March 2022 were examined. Mycophenolate mofetil (MMF) was administered preoperatively in DSA-positive cases with positive lymphocyte cross-matching who underwent LDLT. In those with strongly positive DSA (mean fluorescence intensity 10 000), rituximab was administered 2 weeks before LDLT in addition to MMF. Cross-reactive epitope group antigen (CREG)-alone-positive cases were also treated with preoperative MMF when lymphocyte cross-matching was positive. RESULTS Of the 37 patients, 9 were DSA-positive, 7 were CREG-alone-positive, and the others were double-negative. Of 9 DSA-positive cases, desensitization therapy was performed in 7, among which rituximab administration was performed in 3 strongly DSA-positive cases. Of 7 CREG-alone-positive cases, 2 were lymphocyte cross-match-positive and underwent desensitization therapy. The 1-year survival rate was 100% in both DSA- and CREG-alone-positive cases. The frequency of T-cell mediated rejection in DSA-positive, CREG-alone-positive, and double-negative cases was 22%, 43%, and 29%, respectively, with no significant difference. Antibody-mediated rejection occurred in only 1 patient, who was strongly DSA-positive and blood-group incompatible. There was also no significant difference among the 3 groups in terms of the frequency of biliary complications or 90-day mortality. CONCLUSIONS Satisfactory LDLT results were achieved in DSA- and CREG-alone-positive cases following desensitization therapy.

Contemporary outcomes of pediatric cardiac transplantation with a positive retrospective crossmatch.

A positive crossmatch (+ XM) has traditionally been associated with adverse outcomes following pediatric heart transplantation. However, more recent studies suggest that favorable intermediate-term outcomes may be achieved despite a + XM. This study's hypothesis is that children with a + XM have similar long-term survival, but higher rate of complications such as rejection, coronary allograft vasculopathy (CAV), and infection, compared to patients with a negative (-) XM. The Pediatric Heart Transplant Society Registry (PHTS) database was queried from 2010-2021 for all patients <18 years of age with a known XM. Baseline demographics were compared between + XM and - XM groups using appropriate parametric and non-parametric group comparisons. Cox Proportional Hazards Modeling was used to identify risk factors for post-transplant graft loss, rejection, and CAV. Of 4599 pediatric heart transplants during the study period, XM results were available for 3914 (85%), of which 373 (9.5%) had a + XM. Univariate analysis showed lower 10-year survival for patients with + XM (HR = 1.3, p = .04). Multivariate analyses revealed no significant difference in 10-year survival in the 2 groups; however, time to first rejection (p = .0001) remained significantly shorter in the + XM group. Pediatric patients transplanted across a + XM experience earlier rejection; however, after multivariate adjustment, + XM is not independently associated with intermediate-term graft loss. The risk of heart transplantation against a + XM must be balanced with the ongoing risk of waitlist mortality.

Immune response after pig-to-human kidney xenotransplantation: a multimodal phenotyping study

Cross-species immunological incompatibilities have hampered pig-to-human xenotransplantation, but porcine genome engineering recently enabled the first successful experiments. However, little is known about the immune response after the transplantation of pig kidneys to human recipients. We aimed to precisely characterise the early immune responses to the xenotransplantation using a multimodal deep phenotyping approach. We did a complete phenotyping of two pig kidney xenografts transplanted to decedent humans. We used a multimodal strategy combining morphological evaluation, immunophenotyping (IgM, IgG, C4d, CD68, CD15, NKp46, CD3, CD20, and von Willebrand factor), gene expression profiling, and whole-transcriptome digital spatial profiling and cell deconvolution. Xenografts before implantation, wild-type pig kidney autografts, as well as wild-type, non-transplanted pig kidneys with and without ischaemia-reperfusion were used as controls. The data collected from xenografts suggested early signs of antibody-mediated rejection, characterised by microvascular inflammation with immune deposits, endothelial cell activation, and positive xenoreactive crossmatches. Capillary inflammation was mainly composed of intravascular CD68+ and CD15+ innate immune cells, as well as NKp46+ cells. Both xenografts showed increased expression of genes biologically related to a humoral response, including monocyte and macrophage activation, natural killer cell burden, endothelial activation, complement activation, and T-cell development. Whole-transcriptome digital spatial profiling showed that antibody-mediated injury was mainly located in the glomeruli of the xenografts, with significant enrichment of transcripts associated with monocytes, macrophages, neutrophils, and natural killer cells. This phenotype was not observed in control pig kidney autografts or in ischaemia-reperfusion models. Despite favourable short-term outcomes and absence of hyperacute injuries, our findings suggest that antibody-mediated rejection in pig-to-human kidney xenografts might be occurring. Our results suggest specific therapeutic targets towards the humoral arm of rejection to improve xenotransplantation results. OrganX and MSD Avenir.

Kidney transplant outcomes in patients with antibodies to human neutrophil antigen 3a

BackgroundAntibody mediated rejection (ABMR) of kidney transplants has been shown to occur in the absence of a known donor specific antibody to human leucocyte antigen (HLA). Antibodies to the human neutrophil antigen (HNA) system have been detected in kidney transplant recipients and linked to ABMR in the absence of an HLA donor specific antibody (DSA), but there remains limited literature regarding this. MethodsCase series analysis was carried out examining three cases of HNA-3a antibody positive flow cytometry cross match (FC-XM) from two transplant centres in Scotland. ResultsAll patients included were female and had been sensitised as a result of pregnancy. One live donor recipient with HNA-3a antibodies identified prior to transplant received ATG induction and has had a good outcome. The remaining two patients received deceased donor transplants. HNA-3a antibodies were indicated following a retrospective flow cytometry crossmatch. Both patients received Basiliximab induction and both have experienced ABMR requiring supplementary immunosuppression. ConclusionsThe predicted rate of HNA-3a antibodies amongst patients awaiting kidney transplant in the UK is <1%. However, with increasing evidence to support a role for HNA-3a antibodies in the development of ABMR there may be value in screening at risk groups to allow for augmented immunosuppression to be considered at the time of kidney transplant.

SCWOMP Recovery Algorithm for 5G MIMO Communication Symbol Detection

In order to solve the problem of small capacity and high energy consumption in China’s 5G communication technology system, the research proposes that based on the segmented weakly orthogonal matching pursuit (SWOMP) algorithm, it is combined with the compressed sensing matching pursuit algorithm to form a segmented backtracking weak selection positive algorithm and Cross Match Tracking (SCWOMP) algorithm. First, the sparseness of MIMO system technology and its transmission structure is analyzed. Then, the new model is built after comparing with other algorithms, and the problem of overestimating the low recovery probability in the calculation process is improved by the backtracking of the algorithm and the improvement of the angle of the atomic column selection, so as to reduce the number of iterations and improve the performance of the algorithm. The results show that, in the performance comparison of different sampling points under different compressed sensing recovery algorithms, the recovery probability of the SCWOMP algorithm is the best, and when the number of sampling points is 80, although the fixed step size of the SCWOMP algorithm is different, there is recovery. The probability has a maximum value, close to 1. Then, the improved compressed sensing recovery algorithm is simulated and analyzed. When the pruning coefficient is 0.5 and the number of sampling points is 80, the reconstruction rate has a maximum value, and when other algorithms reach the maximum reconstruction rate, the number of sampling points (M) is significantly greater than that of the SCWOMP algorithm. An increase in the rate of reduction of the reconstruction probability of the SCWOMP algorithm is significantly lower than that of other algorithms; when sparsity is equal to 70, the reconstruction probability becomes 0, indicating that SCWOMP has a wider reconfigurable range and has a significant performance effect. This shows that the proposed SCWOMP algorithm has the best detection performance for 5G communication symbol detection, which can effectively increase the capacity of the system and better promote technology.

Second Kidney Transplant Outcomes in Dialysis Dependent Recipients by Induction Type in the United States

We examined the association between induction type for a second kidney transplant in dialysis-dependent recipients and the long-term outcomes. Using the Scientific Registry of Transplant Recipients, we identified all second kidney transplant recipients who returned to dialysis before re-transplantation. Exclusion criteria included: missing, unusual, or no-induction regimens, maintenance regimens other than tacrolimus and mycophenolate, and positive crossmatch status. We grouped recipients by induction type into 3 groups: the anti-thymocyte group (N=9899), the alemtuzumab group (N=1982), and the interleukin 2 receptor antagonist group (N=1904). We analyzed recipient and death-censored graft survival (DCGS) using the Kaplan-Meier survival function with follow-up censored at 10 years post-transplant. We used Cox proportional hazard models to examine the association between induction and the outcomes of interest. To account for the center-specific effect, we included the center as a random effect. We adjusted the models for the pertinent recipient and organ variables. In the Kaplan-Meier analyses, induction type did not alter recipient survival (log-rank P=.419) or DCGS (log-rank P=.146). Similarly, in the adjusted models, induction type was not a predictor of recipient or graft survival. Live-donor kidneys were associated with better recipient survival (HR 0.73, 95% CI [0.65, 0.83], P < .001) and graft survival (HR 0.72, 95% CI [0.64, 0.82], P < .001). Publicly insured recipients had worse recipient and allograft outcomes. In this large cohort of average immunologic-risk dialysis-dependent second kidney transplant recipients, who were discharged on tacrolimus and mycophenolate maintenance, induction type did not influence the long-term outcomes of recipient or graft survival. Live-donor kidneys improved recipient and graft survival.

Impact of early corticosteroid withdrawal on simultaneous pancreas-kidney transplant long-term outcomes: Single center experience and comparison to the International Pancreas Transplant Registry.

There remains a paucity of modern data comparing early steroid withdrawal (ESW) versus chronic corticosteroid (CCS) immunosuppression in simultaneous pancreas kidney (SPK) transplant recipients with long-term follow-up. Therefore, the purpose of this study is to assess the effectiveness and tolerability of ESW compared to CCS post-SPK. This was a retrospective single-center matched comparison with the International Pancreas Transplant Registry (IPTR). Patients from University of Illinois Hospital (UIH) represented the ESW group and were compared to those matched CCS patients from the IPTR. Included patients were adult recipients of a primary SPK transplant between 2003 and 2018 within the US receiving rabbit anti-thymocyte globulin induction. Patients were excluded if they had early technical failures, missing IPTR data, graft thrombosis, re-transplant, or positive crossmatch SPK. A total of 156 patients were matched and included in the analysis. Patients were predominantly African American (46.15%) males (64.1%) with Type 1 diabetes etiology (92.31%). Overall pancreas allograft survival (hazard ratio [HR] = .89, 95% confidence interval [CI] .34-2.30, p = .81) and kidney allograft survival (HR = .80, 95%CI .32-2.03, p = .64) were similar between the two groups. Immunologic pancreas allograft loss was statistically similar at 1-year (ESW 1.3% vs. CCS 0%, p = .16), 5-year (ESW 1.3% vs. CCS 7.7%, p = .16), and 10-year (ESW 11.0% vs. CCS 7.7%, p = .99). The 1-year (ESW 2.6% vs. CCS 0%, p>.05), 5-year (ESW 8.3% vs. CCS 7.0%, p>.05), and 10-year (ESW 22.7% vs. CCS 9.9%, p = .2575) immunologic kidney allograft loss were also statistically similar. There was no difference in 10-year overall patient survival (ESW 76.2% vs. CCS 65.6%, p = .63). No differences were found between allograft or patient survival post-SPK when comparing an ESW or CCS protocol. Future assessment is needed to determine differences in metabolic outcomes.

Successful Pediatric Heart Transplantation from a Deceased Donor with SARS-Cov-2 Infection: A Case Report

We report the case of a 3-year-old who was highly sensitized and received cardiac transplantation from a donor in the acute phase of SARS-CoV-2 infection. Despite maximal immunosuppression owing to a positive cross-match and desensitization protocol, the patient's course was favorable.

#6369 RESULTS OF KIDNEY TRANSPLANTATION IN PATIENTS WITH LOW MFI PREFORMED DONOR SPECIFIC ANTIBODIES

Abstract Background and Aims Preformed DSA at transplantation, significantly increase risk of antibody-mediated rejection (ABMR). While pre-existing positive DSA with concomitant positive cross-match is a general contra-indication to kidney transplantation, DSA presence with negative crossmatch is still a controversial topic. The presence of DSA with Mean Fluorescence Index (MFI) up to 3.000 and a negative cross-match is not valued as a contraindication to transplantation and is widely accepted. In some transplant centers the chance of transplantation is also offered to DSA positive patients, with MFI up to 5.000. Aim of this study was to analyze graft and patient survival, acute cellular rejection, humoral rejection, renal function and side effects in kidney transplant recipients (KTR) with positive DSA (MFI up to 3.000) and negative cross-match. Method Nineteen pts (age 53+/-11) with chronic renal failure on chronic hemodialysis treatment (8+/-6 years) received a kidney transplant between May 2017 and December 2020. Median PRA was 66%; 100% pts had DSA with average MFI 2122 (min 1039, max 3779). As immunosuppressive therapies all pts received induction with Thymoglobuline plus Rituximab, followed by maintenance immunosuppression with Tacrolimus, MofetilMycoFenolate and Steroids. All patients were on periodic follow up in our Transplant Clinic. Mean follow up was 26.5+/-14.4 months. Results were compared to a concomitant KTR group DSA and crossmatch negative. Results After 2y follow-up, 17/19 pts are alive (89.5%), one patient died (1/19, 5.2%) after treatment for ABMR. Three patients returned to dialysis treatment (15.8%) during the first year post-tx, because of: PNF 1pt; irreversible ABMR rejection 2 pts. One other patient had reversible ABMR. Cumulative one year graft survival was 79% and the cumulative incidence of ABMR was 15.8%. Average 2 years follow-up creatinine was 1.46+/-0.88 mg/dl, median 2 year GFR was 51+/-25 ml/min. Comparing the matched control group (19 pts DSA and cross-match negative) 2 years patient survival, graft survival, GFR, acute rejection were not significantly different. Incidence of acute rejection was higher in the DSA positive group (16% vs 0%), as well as graft loss (21% vs 12%). Conclusion Our data suggest that low dose Thymoglobuline plus Rituximab induction allow kidney transplantation in recipient with high PRA (69%) and positive DSA with low MFI (&amp;lt; 3.000), with higher risk of acute rejection, and graft loss.

Impact of allele-specific anti–human leukocyte antigen class I antibodies on organ allocation

Technological advances in the field of histocompatibility have allowed us to define anti–human leukocyte antigen (HLA) antibody specificity at the allelic level. However, how allele-specific antibodies affect organ allocation is poorly studied. We examined allelic specificities of class I HLA antibodies in 6726 consecutive serum samples from 2953 transplant candidates and evaluated their impact on the corresponding crossmatch and organ allocation. Out of 17 class I HLA antigens represented by >1 allele in the LABScreen single antigen bead assay, 12 had potential allele-specific reactivity. Taking advantage of our unbiased cohort of deceased donor-candidate testing (123,135 complement-dependent cytotoxicity crossmatches between 2014 and 2017), we estimated that the presence of allele-specific antibody detected using a single antigen bead assay (median fluorescence intensity, >3000) against only the rare allele was a poor predictor of a positive complement-dependent cytotoxicity crossmatch, with a positive predictive value of 0% to 7%, compared with 52.5% in allele-concordant class I HLA antibodies against A or B locus antigens. Further, we confirmed allele-specific reactivity using flow crossmatch in 3 scenarios: A11:01/A11:02, A68:01/A68:02, and B44:02/B44:03. Our results suggest that allele-specific antibodies may unnecessarily exclude transplant candidates (up to 10%) from organ offers by overcalling unacceptable antigens; incorporation of selective reactivity pattern in allocation may promote precision matching and more equitable allocation.