The Major Role of T Regulatory Cells in the Efficiency of Vaccination in General and Immunocompromised Populations: A Review.

Since their conception with the smallpox vaccine, vaccines used worldwide have mitigated multiple pandemics, including the recent COVID-19 outbreak. Insightful studies have uncovered the complexities of different functional networks of CD4 T cells (T helper 1 (Th1); Th2, Th17) and CD8 T cells (T cytotoxic; Tc), as well as B cell (BIgM, BIgG, BIgA and BIgE) subsets, during the response to vaccination. Both T and B cell subsets form central, peripheral, and tissue-resident subsets during vaccination. It has also become apparent that each vaccination forms a network of T regulatory subsets, namely CD4+ CD25+ Foxp3+ T regulatory (Treg) cells and interleukin-10 (IL-10)-producing CD4+ Foxp3- T regulatory 1 (Tr1), as well as many others, which shape the quality/quantity of vaccine-specific IgM, IgG, and IgA antibody production. These components are especially critical for immunocompromised patients, such as older individuals and allograft recipients, as their vaccination may be ineffective or less effective. This review focuses on considering how the pre- and post-vaccination Treg/Tr1 levels influence the vaccination efficacy. Experimental and clinical work has revealed that Treg/Tr1 involvement evokes different immune mechanisms in diminishing vaccine-induced cellular/humoral responses. Alternative steps may be considered to improve the vaccination response, such as increasing the dose, changing the delivery route, and/or repeated booster doses of vaccines. Vaccination may be combined with anti-CD25 (IL-2Rα chain) or anti-programmed cell death protein 1 (PD-1) monoclonal antibodies (mAb) to decrease the Tregs and boost the T/B cell immune response. All of these data and strategies for immunizations are presented and discussed, aiming to improve the efficacy of vaccination in humans and especially in immunocompromised and older individuals, as well as organ transplant patients.

Impact of single centre kidney-exchange transplantation to increase living donor pool in India: A cohort study involving non-anonymous allocation.

AIM: In India, 85% of organ donations are from living donors and 15% are from deceased donors. One-third of living donors were rejected because of ABO or HLA incompatibility. Kidney exchange transplantation (KET) is a cost-effective and legal strategy to increase living donor kidney transplantation (LDKT) by 25%-35%. METHODS: We report our experience with 539 KET cases and the evolution of a single-centre program to increase the use of LDKT. RESULTS: Between January 2000 and 13 March, 2024, 1382 deceased donor kidney transplantations and 5346 LDKT were performed at our centre, including 10% (n = 539) from KET. Of the 539 KET, 80.9% (n = 436) were ABO incompatible pairs, 11.1% (n = 60) were compatible pairs, and 8% (n = 43) were sensitized pairs. There were 75% 2-way (n = 2 × 202 = 404), 16.2% 3-way (n = 3 × 29 = 87), 3% 4-way (n = 4 × 4 = 16), 1.8% 5-way (n = 5 × 2 = 10), 2.2% 6-way (n = 6 × 2 = 12), and 1.8% 10-way KET (n = 10 × 1 = 10). Of the recipients 81.2% (n = 438) were male and 18.8% (n = 101) were female, while of the donors, 78.5% (n = 423) were female and 21.5% (n = 116) were male. All donors were near relatives; wives (54%, n = 291) and mothers (20%, n = 108) were the most common donors. At a median follow-up of 8.2 years, patient survival, death censored graft survival, acute rejection, and median serum creatinine levels of functioning grafts were 81.63% (n = 440), 91% (n = 494), 9.8% (n = 53) and 1.3 mg/dL respectively. We credited the success to maintaining a registry of incompatible pairs, high-volume LDKT programs, non-anonymous allocation and teamwork. CONCLUSION: This is the largest single-centre KET program in Asia. We report the challenges and solutions to replicate our success in other KET programs.

Recycling transplanted organs: An exceptional case and literature review.

BACKGROUND: Recycling transplant kidneys, in other words using an allograft which has previously been transplanted in one recipient for transplant in a second recipient, can be a source of opportunity for expanding the pool of available grafts in the United States and beyond. SUMMARY: We describe a case of renal transplantation from a donor who had undergone a kidney transplant 3 years prior and had good graft function at the time of procurement. The recipient underwent transplantation uneventfully and to date has demonstrated excellent graft function. We also include a literature review of reported cases of recycled/retransplanted kidneys. KEY MESSAGES: -Recycling transplanted kidneys is a largely untapped resource which could help decrease the transplant waitlist. -Utilizing such kidneys does need special considerations in terms of procurement technique, backtable, crossmatch, recipient selection and follow-up.

Differences in Responses of Immunosuppressed Kidney Transplant Patients to Moderna mRNA-1273 versus Pfizer-BioNTech.

Immunosuppressed kidney transplant (KT) recipients produce a weaker response to COVID-19 vaccination than immunocompetent individuals. We tested antiviral IgG response in 99 KT recipients and 66 healthy volunteers who were vaccinated with mRNA-1273 Moderna or BNT162b2 Pfizer-BioNTech vaccines. A subgroup of participants had their peripheral blood leukocytes (PBLs) evaluated for the frequency of T helper 1 (Th1) cells producing IL-2, IFN-γ and/or TNF-α, and IL-10-producing T-regulatory 1 (Tr) cells. Among KT recipients, 45.8% had anti-SARS-CoV-2 IgG compared to 74.1% of healthy volunteers (p = 0.009); also, anti-viral IgG levels were lower in recipients than in volunteers (p = 0.001). In terms of non-responders (≤2000 U/mL IgG), Moderna's group had 10.8% and Pfizer-BioNTech's group had 34.3% of non-responders at 6 months (p = 0.023); similarly, 15.7% and 31.3% were non-responders in Moderna and Pfizer-BioNTech groups at 12 months, respectively (p = 0.067). There were no non-responders among controls. Healthy volunteers had higher Th1 levels than KT recipients, while Moderna produced a higher Th1 response than Pfizer-BioNTech. In contrast, the Pfizer-BioNTech vaccine induced a higher Tr1 response than the Moderna vaccine (p < 0.05); overall, IgG levels correlated with Th1(fTTNF-α)/Tr1(fTIL-10) ratios. We propose that the higher number of non-responders in the Pfizer-BioNTech group than the Moderna group was caused by a more potent activity of regulatory Tr1 cells in KT recipients vaccinated with the Pfizer-BioNTech vaccine.

Concomitant Polyoma BK Virus and West Nile Virus in Renal Allografts.

Surveillance of the renal allograft recipient is essential when monitoring renal function to detect the early onset of rejection and alter therapeutic treatments to treat acute rejection or other causes and improve long-term graft function. If renal function begins to deteriorate, a renal biopsy is often indicated to assess the Banff grade of potential rejection or other causes, especially in the setting of polyoma BK viral load elevation. Although BK infection in the allograft is asymptomatic, reactivation of the virus is known to be associated with the acceleration of pathologic change and a poor outcome in the allograft. BK reactivation in a transplant kidney is not uncommon, and determining inflammation related to the virus versus acute rejection is paramount for appropriate immunosuppressive therapy management. We identified a concomitant polyoma BK virus and West Nile Virus (WNV) infection in two renal transplant patients which, to our knowledge, has not previously been reported. However, other concomitant infections have been reported in renal allografts including BK virus and cytomegalovirus (CMV), CMV and hepatitis C (HCV), and HCV and human immunodeficiency virus (HIV). As WNV has become endemic in many regions of the United States, and since the transmission of the virus via transplanted organs is associated with significant morbidity and mortality, it may be prudent to consider serologic screening for WNV in living donors prior to organ procurement. Regardless, the observation we made and report here should underscore the potential for concomitant viral infections that may be masked when a renal allograft has a significant inflammatory response to BK virus.

Characterizing the risk of human leukocyte antigen-incompatible living donor kidney transplantation in older recipients.

Older compatible living donor kidney transplant (CLDKT) recipients have higher mortality and death-censored graft failure (DCGF) compared to younger recipients. These risks may be amplified in older incompatible living donor kidney transplant (ILDKT) recipients who undergo desensitization and intense immunosuppression. In a 25-center cohort of ILDKT recipients transplanted between September 24, 1997, and December 15, 2016, we compared mortality, DCGF, delayed graft function (DGF), acute rejection (AR), and length of stay (LOS) between 234 older (age ≥60 years) and 1172 younger (age 18-59 years) recipients. To investigate whether the impact of age was different for ILDKT recipients compared to 17 542 CLDKT recipients, we used an interaction term to determine whether the relationship between posttransplant outcomes and transplant type (ILDKT vs CLDKT) was modified by age. Overall, older recipients had higher mortality (hazard ratio: 1.632.072.65, P < .001), lower DCGF (hazard ratio: 0.360.530.77, P = .001), and AR (odds ratio: 0.390.540.74, P < .001), and similar DGF (odds ratio: 0.461.032.33, P = .9) and LOS (incidence rate ratio: 0.880.981.10, P = 0.8) compared to younger recipients. The impact of age on mortality (interaction P = .052), DCGF (interaction P = .7), AR interaction P = .2), DGF (interaction P = .9), and LOS (interaction P = .5) were similar in ILDKT and CLDKT recipients. Age alone should not preclude eligibility for ILDKT.

Electronic Patient Portal Use After Kidney Transplant: A Single-Center Retrospective Study.

INTRODUCTION: Online patient portals have become a core component of patient-centered care. Limited research exists on such portal use in patients after kidney transplantation. The aim of this study was to examine preoperative, perioperative, and postoperative factors associated with post-transplantation portal use. METHODS: This cross-sectional study included all patients who underwent kidney transplantation from April 2016 to May 2019 at the University of Toledo Medical Center. Exclusion criteria included international travel for transplantation and those without available postoperative lab or follow-up records. Data were collected for 2 y post-transplantation. Univariable and multivariable linear regression was performed to determine associations with portal use. RESULTS: Two hundred and forty-seven kidney transplant recipients were included in the study; 35.6% (n = 88) used the portal versus 64.4% (n = 159) did not. Preoperative factors associated with increased use included income >$40,000 (odds ratio [OR], 2.95; P = 0.006) and cancer history (OR, 2.46; P = 0.007), whereas diabetes history had reduced use (OR, 0.51; P = 0.021). The Black race had the least use. Perioperatively, reduced use was associated with dialysis before transplant (OR, 0.25; P < 0.001) and hospital stay ≥4 d (OR, 0.49; P = 0.009). Postoperatively, associations with increased use included average eGFR >30 (P = 0.04) and hospital readmissions (n = 102), whereas those with ER (n = 138) visits had decreased use. Multivariable analysis revealed increased use with income >$40,000 (OR, 2.51; P = 0.033). CONCLUSIONS: There was no observed difference in clinical outcomes for portal users and nonusers undergoing kidney transplantation, although portal use may decrease the likelihood of ER visits. Socioeconomic status and ethnicity may play a role on who utilizes the patient portals.

Brain-type natriuretic peptide levels and invasive hemodynamic parameters in dialysis dependent patients.

BACKGROUND: Pulmonary hypertension (PH) is associated with increased mortality in patients with end-stage renal disease (ESRD). The prevalence of PH within ESRD as measured by right heart catheterization (RHC) is poorly described, and the correlation of BNP to pulmonary artery pressure (PAP) is unknown. METHODS: The renal transplant database at our center was used to identify adult ESRD patients from July 2013 to July 2015 who had a plasma BNP level measurement and invasive hemodynamic assessment by RHC within a 1-month period. Pulmonary hypertension was defined as a mean pulmonary artery pressure (PAP) ≥ 25 mmHg. Multivariate linear regression analysis was used to identify correlations between BNP and RHC parameters. To estimate the utility of BNP in the screening of PH, a receiver-operating characteristic (ROC) curve was generated. RESULTS: Eighty-eight patients were included in the study of which 43 had PH. Compared to patients without PH, BNP was significantly higher within the PH cohort (1619 ± 2602 pg/ml vs. 352 ± 491 pg/ml). A statistically significant association (r [86] = 0.60, p<0.001) between plasma BNP and mean PAP was identified. ROC curve indicated an acceptable predictive value of BNP in PH with a c-statistic of 0.800 (95% CI 0.708 - 0.892). CONCLUSIONS: In ESRD patients being considered for renal transplantation, PH is highly prevalent and BNP levels are elevated and significantly correlated with higher PAP. BNP may be a useful non-invasive marker of PH in these patients.

Living Kidney Donor Transplantation and Global Kidney Exchange.

Global kidney exchange offers an opportunity to expand living donor kidney transplants internationally to patients with immunologic barriers. The concept has been proven to be successful in a limited number of transplants. However, a number of misconceptions have created obstacles to its development. We suggest that a systematic application of this innovative tool would offer opportunities to treat thousands of patients worldwide who are presently denied a transplant and often even access to dialysis.

False Positive Pregnancy Test Before Kidney Transplant: Case Report and Review of Literature.

Pregnancy tests are routinely done before any surgery under general anesthesia including kidney transplantation. Positive test usually leads to more investigations to detect a possible pregnancy or malignancy and the surgery gets canceled or postponed. Because a kidney transplant from a deceased donor is not elective, it usually gets canceled in this scenario. Some groups have reported on normally elevated human chorionic gonadotrophin (hCG) levels in perimenopausal women and in patients with chronic kidney disease. This is thought to be from the pituitary. We present a highly sensitized prospective kidney transplant recipient with a positive pregnancy test with low levels of serum human chorionic gonadotrophin. She underwent additional preoperative testing after which we proceeded with the kidney transplant. Herein, we discuss the management of patients who have an unexpected positive pregnancy test before transplant.

Kidney Paired Donation Chains Initiated by Deceased Donors.

Introduction: Rather than generating 1 transplant by directly donating to a candidate on the waitlist, deceased donors (DDs) could achieve additional transplants by donating to a candidate in a kidney paired donation (KPD) pool, thereby, initiating a chain that ends with a living donor (LD) donating to a candidate on the waitlist. We model outcomes arising from various strategies that allow DDs to initiate KPD chains. Methods: We base simulations on actual 2016 to 2017 US DD and waitlist data and use simulated KPD pools to model DD-initiated KPD chains. We also consider methods to assess and overcome the primary criticism of this approach, namely the potential to disadvantage blood type O-waitlisted candidates. Results: Compared with shorter DD-initiated KPD chains, longer chains increase the number of KPD transplants by up to 5% and reduce the number of DDs allocated to the KPD pool by 25%. These strategies increase the overall number of blood type O transplants and make LDs available to candidates on the waitlist. Restricting allocation of blood type O DDs to require ending KPD chains with LD blood type O donations to the waitlist markedly reduces the number of KPD transplants achieved. Conclusion: Allocating fewer than 3% of DD to initiate KPD chains could increase the number of kidney transplants by up to 290 annually. Such use of DDs allows additional transplantation of highly sensitized and blood type O KPD candidates. Collectively, patients of each blood type, including blood type O, would benefit from the proposed strategies.

Improving Access to HLA-Matched Kidney Transplants for African American Patients.

Introduction: Kidney transplants fail more often in Black than in non-Black (White, non-Black Hispanic, and Asian) recipients. We used the estimated physicochemical immunogenicity for polymorphic amino acids of donor/recipient HLAs to select weakly immunogenic kidney transplants for Black vs. White or non-Black patients. Methods: OPTN data for 65,040 donor/recipient pairs over a 20-year period were used to calculate the individual physicochemical immunogenicity by hydrophobic, electrostatic and amino acid mismatch scores (HMS, EMS, AMS) and graft-survival outcomes for Black vs. White or vs. non-Black recipients, using Kaplan-Meier survival and Cox regression analyses. Simulations for re-matching recipients with donors were based on race-adjusted HMS thresholds with clinically achievable allocations. Results: The retrospective median kidney graft survival was 12.0 years in Black vs. 18.6 years in White (6.6-year difference; p>0.001) and 18.4 years in non-Black (6.4-year difference; p>0.01) recipients. Only 0.7% of Blacks received transplants matched at HLA-A/B/DR/DQ (HMS=0) vs. 8.1% in Whites (p<0.001). Among fully matched Blacks (HMS=0), graft survival was 16.1-years and in well-matched Blacks (HMS ≤ 3.0) it was 14.0-years. Whites had 21.6-years survival at HMS ≤ 3.0 and 18.7-years at HMS ≤ 7.0 whereas non-Blacks had 22.0-year at HMS ≤ 3.0 and 18.7-year at HMS ≤ 7.0, confirming that higher HMS thresholds produced excellent survival. Simulation of ABO-compatible donor-recipient pairs using race-adjusted HMS thresholds identified weakly immunogenic matches at HMS=0 for 6.1% Blacks and 18.0% at HMS ≤ 3.0. Despite prioritizing Black patients, non-Black patients could be matched at the same level as in current allocation (47.0% vs 56.5%, at HMS ≤ 7.0). Conclusions: Race-adjusted HMS (EMS, AMS)-based allocation increased the number of weakly immunogenic donors for Black patients, while still providing excellent options for non-Black recipients.

The Sun Is Still Shining: Nature of Industry Payments to Transplant Surgeons From 2014 to 2019.

Background: Established in 2013, the Open Payments Program (OPP) mandated that medical device and pharmaceutical manufacturers submit record of any financial incentive given to physicians to the Centers for Medicare and Medicaid Services, which is in turn made publicly available. This study aims to characterize these payments to transplant surgeons over the first 6 y of OPP data. Methods: The study sample included all physicians who received at least one nonresearch payment as transplant surgeons to the OPP. To capture transplant surgeons who may be listed under their pipeline specialty, the American Society of Transplant Surgeons member directory as of January 2021 was queried. Payments were analyzed temporally, geographically, and by payment type, physician, and industry payer. Results: In total, payments totaling $15 661 536 were made to 1335 transplant surgeons over the study period. The mean payment was $436.90 (SD, $1760), and the median payment was $52.94 (interquartile range, $18.29-$159.80). The top contributing companies were Intuitive Surgical, Inc.; Gilead Sciences, Inc.; and Novartis Pharmaceuticals. Only 5.3% ($827 236) was paid toward faculty or as a speaker for a nonaccredited and noncertified continuing education program and honorarium. Educational payments came in at $1 233 141 (7.9%) over the study period. $13 750 828.60 (87.8%) of the payments were for other categories (consulting fees, food and beverages, etc). Organ transplant and procurement region 7 and 8 transplant surgeons received the highest median payments during the study period. Conclusions: This study is the first to characterize the payments made to transplant surgeons since the passage of the Sunshine Act. Further studies are needed to understand and interpret the relationship between industry and transplant surgeons, as the payments may or may not translate to influence in medical decisions or use of medical devices.

Serum bilirubin as a predictor of graft outcomes after renal transplant.

Bilirubin is a signaling molecule that alters the immune response and metabolism. While bilirubin has been employed as a marker of renal and cardiovascular health, its role in renal transplant recipients is not known. In this study, we sought to determine the impact of bilirubin (total, direct and indirect) on the estimated glomerular filtration rate (eGFR) after renal transplantation. We conducted a retrospective review of pre- and postoperative bilirubin levels in 457 renal transplant recipients at a single center. Pre- and post-rejection bilirubin levels were also assessed in those patients who experienced a rejection episode. No statistically significant differences were found in bilirubin levels during the pre-transplant to post-rejection period among patients who experienced rejection with kidney allograft survival. No statistically significant associations were observed between baseline bilirubin and post-transplant eGFR in the full patient group or within the gender- or race-stratified groups. Baseline bilirubin was not correlated with time to rejection. Our results suggest that bilirubin may not offer renoprotection in renal transplant recipients.

Optimal Timing of COVID-19 Vaccination in the Peri-Transplant Period: A Single Institution Case Series.

The outcomes of vaccination against Severe Acute Respiratory Syndrome Coronavirus 2 in organ transplant recipients are unclear. Recent studies have investigated outcomes for patients who are several years post transplant. There has not been much data in peri-transplant patients. This is important because patients are highly immunosuppressed during this period owing to induction immunosuppression and are thus susceptible to infection. We looked at 6 patients who were transplanted at our center after receiving their first dose of mRNA vaccines. We assessed their antibody response after 1, 2, and in two patients, 3 doses of the vaccine. Out of the two patients who received their third booster dose, one had a detectable antibody level after the third dose. We report that the overall antibody response to vaccination was weaker in transplant patients compared with the general population, with a rapid attrition of antibody response over time. There is a need for more studies that follow-up antibody levels in transplant patients over time, especially those in the peri-transplant period to help guide the vaccination plan for immunosuppressed transplant patients.

The use of digital magnification to reduce radiation dose in the cardiac catheter laboratory.

OBJECTIVES: To audit whether using magnification of images by use of a large viewing screen using digital matrix magnification which enlarges the image by 33% without using the X-ray machine zoom magnification protocols on a Siemens Artis Zee X-ray machine in a cardiac catheter laboratory results in a reduction of kerma-area product (KAP) for both diagnostic and interventional procedures. This reduction was predicted in an in vitro study in our laboratory, which has previously shown a 20.4% reduction in KAP. METHODS: A retrospective analysis was conducted of the radiation exposure to compare the measured KAP recorded during the period when conventional magnification with automatic brightness and dose control was used on a Siemens Artis Zee X-ray machine with a flat panel detector and when magnification settings were avoided by using a large screen to enlarge and project a non-magnified image by digital magnification. The analysis was carried out for patients having a diagnostic coronary angiogram and those having an interventional coronary procedure. RESULTS: For diagnostic coronary angiograms the median KAP per procedure in the period using conventional magnification was 2124.5 µGy.m2 compared to 1401 µGy.m2 when image matrix magnification was used, a 34% reduction (p < 0.0001). For interventional coronary procedures, the median KAP per procedure in the period using conventional magnification was 3791 µGy.m2 compared to 2568.5 µGy.m2 when image matrix magnification was used, a 32% reduction (p < 0.0001). CONCLUSION: Avoiding using conventional magnification in the cardiac catheter laboratory and using a large screen to magnify images was associated with a statistically significant greater than 30% reduction in KAP. ADVANCES IN KNOWLEDGE: This paper is the proof in clinical practice of a theoretical conclusion that radiation dose (KAP) is reduced by use of Image matrix magnification using a large viewing screen without the need to use X-ray tube magnification without significant loss of image resolution in interventional cardiology. The same approach will be useful in interventional radiology.

Treatment of chronic total occlusion with percutaneous coronary intervention is associated with improved survival as compared to medical treatment alone: insights from a single-centre registry.

Symptom relief is currently the main indication to perform percutaneous coronary intervention (PCI) of chronic total occlusion (CTO). So far, none of the randomized trials for CTO treatment have demonstrated improved survival after PCI compared to optimal medical treatment (OMT) alone. We investigated whether CTO PCI in addition to OMT could improve survival over OMT alone. Data of 1004 patients with a treated CTO was analysed. Patients with acute coronary syndrome and who underwent coronary artery bypass graft surgery (CABG) were excluded, thus final study population was 378. According to the treatment received, patients were divided into two groups: CTO PCI + OMT (n = 163) and OMT alone (n = 215). The primary endpoint was all-cause mortality during follow-up. The incidence of myocardial infarction (MI), revascularization (both CTO artery and non-CTO artery related) and stroke were also analysed as a secondary outcome. The mean follow-up period was 3.55 ± 0.93 years. Multiple regression analysis was performed to identify independent predictors of all-cause mortality. Occurrence of MI and repeat revascularization (both CTO vessel related and non-CTO vessel) and stroke did not differ significantly between groups. However, all-cause mortality was more frequent in OMT (19.1%) patients than PCI (10.4%). Patients age ≤70 years (odds ratio (OR) 0.47 [0.26; 0.84], p = 0.01) and CTO PCI (OR 0.51 [0.27; 0.94], p = 0.03) were independent predictors of reduced likelihood of all-cause death. The data from our centre registry demonstrates that CTO PCI is associated with reduced all-cause mortality as compared to medical treatment alone in a real-life setting.

Global kidney chains.

Kidney failure is a worldwide scourge, made more lethal by the shortage of transplants. We propose a way to organize kidney exchange chains internationally between middle-income countries with financial barriers to transplantation and high-income countries with many hard to match patients and patient-donor pairs facing lengthy dialysis. The proposal involves chains of exchange that begin in the middle-income country and end in the high-income country. We also propose a way of financing such chains using savings to US health care payers.

Equilibrium Allocations under Alternative Waitlist Designs: Evidence from Deceased Donor Kidneys Kidneys.

Waitlists are often used to ration scarce resources, but the trade-offs in designing these mechanisms depend on agents' preferences. We study equilibrium allocations under alternative designs for the deceased donor kidney waitlist. We model the decision to accept an organ or wait for a preferable one as an optimal stopping problem and estimate preferences using administrative data from the New York City area. Our estimates show that while some kidney types are desirable for all patients, there is substantial match-specific heterogeneity in values. We then develop methods to evaluate alternative mechanisms, comparing their effects on patient welfare to an equivalent change in donor supply. Past reforms to the kidney waitlist primarily resulted in redistribution, with similar welfare and organ discard rates to the benchmark first come first served mechanism. These mechanisms and other commonly studied theoretical benchmarks remain far from optimal. We design a mechanism that increases patient welfare by the equivalent of an 18.2 percent increase in donor supply.