The fate of anti-HLA antibodies following liver transplantation.

Introduction: Liver transplant recipients may have pre-formed anti-HLA antibodies directed to mismatched HLA of the liver donor (donor specific antibodies, DSA) or not directed to the liver donor (non-donor specific, non-DSA). We observed the fate of these antibodies (DSA and non-DSA) at 12 months after transplant. Methods: Patients transplanted between 4/2015 and 12/2018 (N = 216) who had anti-HLA antibody measurements at both transplant and 12 months posttransplant (N = 124) and with DSAs at transplant (N = 31) were considered informative for a paired analysis of the natural history of DSA and non-DSA following liver transplantation. Results: Class I DSAs and non-DSAs decreased between transplant and 12 months; however, Class I DSAs essentially disappeared by 12 months while Class I non-DSAs did not. Anti-HLA Class II DSAs performed differently. While there was a significant drop in values between transplant and 12 months, these antibodies mostly persisted at a low level. Discussion: Our study demonstrated a significant difference in the kinetics of DSA compared to non-DSA following liver transplantation, most profoundly for anti-HLA Class I antibodies. Class I DSAs were mostly absent at 12 months while Class II DSAs persisted, although at lower levels. The mechanisms of reduction in anti-HLA antibodies following liver transplantation are not completely understood and were not pursued as a part of this study. This detailed analysis of Class I and Class II DSAs and non-DSAs represents and important study to explore the change in antibodies at one year from liver transplantation.

Sustained Response to Eculizumab in a Patient With COVID-19-Associated Acute Thrombotic Microangiopathy of the Allograft Kidney: A Case Report.

Acute thrombotic microangiopathy (TMA) developing in association with SARS-CoV-2 infection is a rare but recognized phenomenon in native kidneys. In the allograft kidney, a diagnosis of TMA has a broad etiologic differential, including antibody-mediated rejection and recurrent and de novo causes of TMA that affect the native kidney. Prior case reports have described plasma exchange or eculizumab use in patients with COVID-19-associated TMA. Herein, we describe the course of a kidney transplant patient with COVID-19-associated TMA with response to eculizumab that was sustained after medication withdrawal and review the literature on COVID-19-associated TMA of the allograft kidney.

Time for reform in transplant program-specific reporting: AST/ASTS transplant metrics taskforce.

In accordance with the National Organ Transplant Act and Department of Health and Human Services' Final Rule, the Scientific Registry of Transplant Recipients (SRTR) publicly releases biannual program-specific reports that include analyses of transplant centers' risk-adjusted waitlist mortality, organ acceptance ratios, transplant rates, and graft and patient survival. Since the inception of these center metrics, 1-year posttransplant graft and patient survival have improved, and center variation has decreased, casting uncertainty on their clinical relevance. The SRTR has recently modified center evaluations by ranking centers into 5 tiers rather than 3 tiers in an attempt to discriminate between programs performing within a tight range, further exacerbating this uncertainty. The American Society of Transplantation/American Society of Transplant Surgeons convened an expert taskforce to examine both the utility and unintended consequences of transplant center metrics. Estimates of center variation in outcomes in adjacent tiers are imprecise and fleeting, but can result in consequential changes in clinician and center behavior. The taskforce has concerns that current metrics, based principally on 1-year graft and patient survival, provide minimal if any benefit in informing patient choice and access to transplantation, with the untoward effect of decreased utilization of organs and restriction of research and innovation.

Kidney Biopsy Adequacy: A Metric-based Study.

There are differences in renal biopsy yield related to on-site evaluation, tissue division, and operator, among others. To understand these variations, we collected adequacy-associated data (%cortex, glomeruli, arteries, length) from consecutive native and allograft kidney biopsies over a 22-month period. In total, 1332 biopsies (native: 873, allograft: 459) were included, 617 obtained by nephrologists, 663 by radiologists, and 559 with access to on-site division. Proceduralists with access to on-site evaluation had significantly lower inadequacy rates and better division of tissue for light microscopy (LM), immunofluorescence, and electron microscopy than those without access to on-site evaluation. Radiologists in our region were significantly less likely to have access to on-site evaluation than nephrologists. On multivariate analysis for native kidney biopsies, the effect of having a radiologist perform the biopsy and having access to on-site division were both significant predictors of obtaining greater calculated amount of cortex for LM. Despite the trend for radiologists to obtain more tissue in general, biopsies from nephrologists contained a greater percentage of cortex and were more likely to be considered adequate for LM (native kidney inadequacy rate for LM: 1.11% vs. 5.41%, P=0.0086). Biopsies in which inadequate or marginal cortical tissue was submitted for LM had only minor decreases in the amount of cortex submitted for immunofluorescence and electron microscopy, revealing an opportunity for improved specimen triaging when limited tissue is obtained. In conclusion, both on-site evaluation/division and proceduralist significantly affect quantitative kidney biopsy metrics, which in turn affects the pathologist's ability to render an accurate diagnosis with appropriate prognostic information for the patient and treating nephrologist.

Donor-specific antibodies require preactivated immune system to harm renal transplant.

BACKGROUND: It is an unresolved issue why some kidney transplant recipients with pretransplant donor-specific HLA antibodies (DSA) show a high transplant failure rate, whereas in other patients DSA do not harm the graft. We investigated whether help from preactivated T-cells might be necessary for DSA to exert a deleterious effect. METHODS: The impact of pretransplant DSA and immune activation marker soluble CD30 (sCD30) on 3-year graft survival was analyzed in 385 presensitized kidney transplant recipients. FINDINGS: A deleterious influence of pretransplant DSA on graft survival was evident only in patients who were positive for the immune activation marker sCD30. In the absence of sCD30 positivity, 3-year graft survival was virtually identical in patients with or without DSA (83.1±3.9% and 84.3±2.8%, P=0.81). A strikingly lower 3-year graft survival rate of 62.1±6.4% was observed in patients who were both sCD30 and DSA positive (HR 2.92, P<0.001). Even in the presence of strong DSA with ≥5000 MFI, the 3-year graft survival rate was high if the recipients were sCD30 negative. INTERPRETATION: Pretransplant DSA have a significantly deleterious impact on graft survival only in the presence of high pretransplant levels of the activation marker sCD30.

Hypercoagulability in Kidney Transplant Recipients.

Thrombosis remains an important complication after kidney transplantation. Outcomes for graft and deep vein thrombosis are not favorable. The majority of early kidney transplant failure in adults is due to allograft thrombosis. Risk stratification, early diagnosis, and appropriate intervention are critical to the management of thrombotic complications of transplant. In patients with end-stage renal disease, the prevalence of acquired risk factors for thrombosis is significantly high. Because of hereditary and acquired risk factors, renal transplant recipients manifest features of a chronic prothrombotic state. Identification of hereditary thrombotic risk factors before transplantation may be a useful tool for selecting appropriate candidates for thrombosis prophylaxis immediately after transplantation. Short-term anticoagulation may be appropriate for all patients after kidney transplantation.

Association of Kidney Graft Loss With De Novo Produced Donor-Specific and Non-Donor-Specific HLA Antibodies Detected by Single Antigen Testing.

BACKGROUND: The association of donor-specific HLA antibodies (DSA) with kidney graft failure has been addressed previously; however, the majority of studies were based on small numbers of patients with graft failure. METHODS: We investigated 83 patients with failed kidney transplants for a possible association of de novo development and persistence or loss of pre-existing DSA with graft failure. Single Antigen Bead assay-detected DSA and non-DSA antibodies were compared between patients with graft loss and matched controls with functioning grafts. RESULTS: The incidence of weak de novo DSA or non-DSA at a mean fluorescence intensity of 500 or higher was higher in the graft loss than in the nonrejector group (76% vs 40%, P < 0.001). Because of the low number of patients developing de novo DSA, the DSA results did not reach statistical significance (only 22% of patients with graft loss developed de novo DSA). However, at all cutoffs, there was a significantly higher rate of graft loss in patients with de novo non-DSA. The incidence of strong pretransplant DSA that persist after transplantation was higher in the graft loss group (10% vs 1%, P = 0.034). When C1q-binding ability in sera of rejectors and nonrejectors with posttransplant de novo or persistent DSA was compared, none of the nonrejectors demonstrated C1q positivity, whereas 43% of patients with graft loss showed C1q-positive antibodies, although not necessarily donor-specific (P < 0.001). CONCLUSIONS: Our data show that the posttransplant presence of persisting or de novo HLA antibodies, especially if C1q binding, is associated with graft loss, even if the antibodies are not specific for mismatched donor HLA.

Tacrolimus exposure in the real world: an analysis from the Mycophenolic acid Observational REnal transplant study.

Tacrolimus exposure and renal function data to 36 months post-transplant were analyzed from the prospective, observational Mycophenolic acid Observational REnal transplant (MORE) registry in which de novo kidney transplant patients were managed according to local practice. Tacrolimus trough (C0 ) concentration at month 12 was stratified as low (<6 ng/mL), moderate (6-8 ng/mL), or high (>8 ng/mL) in 724 patients. Estimated glomerular filtration rate (eGFR) was stratified as low (<60 mL/min/1.73 m(2) ) or high (≥60 mL/min/1.73 m(2) ). High tacrolimus C0 (>8 ng/mL) was observed in 47.7%, 34.1%, 26.8%, and 26.7% of patients at baseline and months 12, 24, and 36, respectively. Biopsy-proven acute rejection was similar to month 36 regardless of tacrolimus C0 category at month 12. Tacrolimus C0 >8 ng/mL vs. <6 ng/mL at month 12 was predictive of low eGFR at month 24 (p = 0.023) with a nonsignificant trend at month 36 (p = 0.085). Infections (p < 0.013) and BK virus infection (p < 0.001) were most frequent in the low tacrolimus C0 cohort. Neutropenia was most frequent in the high tacrolimus C0 category (p = 0.010). In conclusion, over a quarter of patients were exposed to high tacrolimus C0 to 36 months post-transplant. Tacrolimus exposure did not affect rejection risk, but tacrolimus C0 >8 ng/mL at month 12 was predictive of subsequent low eGFR compared to C0 <6 ng/mL.

An update on the impact of pre-transplant transfusions and allosensitization on time to renal transplant and on allograft survival.

BACKGROUND: Blood transfusions have the potential to improve graft survival, induce sensitization, and transmit infections. Current clinical practice is to minimize transfusions in renal transplantation candidates, but it is unclear if the evidence continues to support pre-transplant transfusion avoidance. Changes in the Medicare prospective payment system may increase transfusion rates. Thus there is a need to re-evaluate the literature to improve the management options for renal transplant candidates. METHODS: A review applying a systematic approach and conducted using MEDLINE(®), Embase(®), and the Cochrane Library for English-language publications (timeframe: 01/1984-03/2011) captured 180 studies and data from publically available registries and assessed the impact of transfusions on allosensitization and graft survival, and the impact of allosensitization on graft survival and wait time. RESULTS: Blood transfusions continued to be a major cause of allosensitization, with allosensitization associated with increased rejection and graft loss, and longer wait times to transplantation. Although older studies showed a beneficial effect of transfusion on graft survival, this benefit has largely disappeared in the post-cyclosporine era due to improved graft outcomes with current practice. Recent data suggested that it may be the donor-specific antibody component of allosensitization that carried the risk to graft outcomes. CONCLUSIONS: Results of this review indicated that avoiding transfusions whenever possible is a sound management option that could prevent detrimental effects in patients awaiting kidney transplantation.

African American living-kidney donors should be screened for APOL1 risk alleles.

The adjusted rate of end-stage kidney disease (ESKD) among African Americans is markedly increased relative to European Americans. African Americans are overrepresented on the kidney transplantation waiting list and experience longer wait times. In aggregate, these pressures drive recommendations for living donor transplantation. Genovese et al. recently implicated the APOL1 gene in ESKD risk among African Americans (Genovese et al. Science 2010; 329: 841). The presence of two APOL1 risk alleles doubles the relative risk for ESKD; moreover, the alleles are prevalent among African Americans. We propose a strategy for screening for the presence of APOL1 risk alleles among African American living kidney donors and for living-related donors for African American recipients.

Glomerular fibrin thrombi in ABO and crossmatch compatible renal allograft biopsies.

Glomerular fibrin thrombi may be an early indication of antibody-mediated rejection in renal allograft biopsies. However, fibrin thrombi have a broad differential; thus, we sought to evaluate the etiology and implications of glomerular fibrin thrombi in allograft biopsies of blood group and cytotoxic crossmatch compatible renal allografts. Biopsies were identified from the pathology files of Oregon Health & Science University. Detailed histopathologic findings were retrospectively correlated with clinical data, treatment, and outcome. Sixteen early posttransplant biopsies had glomerular fibrin thrombi, including three surveillance biopsies. Six of 16 biopsies had no other histopathologic findings; 5/16 had glomerulitis and peritubular capillaritis; 4/16 had concomitant cellular vascular rejection; one had parenchymal infarction. C4d staining was positive in 4/16 cases. Most patients were treated with IVIg and plasmapheresis, others with rapamycin, thymoglobulin, or rituximab. At an average follow-up of 62 months, 8 patients with functioning grafts had a mean serum creatinine of 1.4 mg/dL (122 µmol/L). Antibody-mediated rejection is an important consideration in blood group compatible allograft biopsies with glomerular fibrin thrombi, even with C4d-negative biopsies. However, multidisciplinary evaluation is necessary, given other etiologies, including drug toxicity, hemolytic-uremia syndrome, and large vessel thrombosis. Despite aggressive treatment, both short and long-term graft survival may be compromised.

Pancreas allograft rejection: analysis of concurrent renal allograft biopsies and posttherapy follow-up biopsies.

BACKGROUND: Pancreas and kidney allograft function is routinely monitored with serum studies (amylase, lipase, and creatinine). Increased levels commonly prompt tissue biopsy, to diagnose cause of graft dysfunction. Historically, pancreas allografts were infrequently biopsied, although serum enzymes and renal rejection may be poor surrogates for pancreas status. METHODS: Pancreas allograft biopsies at our center were reviewed and reclassified according to University of Maryland (UMD) and Banff criteria; C4d immunostaining was performed. Findings were correlated with clinical data and renal allograft biopsies. RESULTS: Fifty-six pancreas allograft biopsies from 27 patients were evaluated. UMD and Banff grading were similar, although two UMD "indeterminate" biopsies were Banff grade 1 rejection. There were 21 concurrent pancreas and renal biopsies, all from simultaneous pancreas-kidney allograft recipients. Thirteen pairs were concordant for rejection; eight pairs were discordant for rejection (38%); six pairs showed pancreas rejection without kidney rejection, and two pairs showed the converse. Fourteen patients had a total of 21 follow-up pancreas allograft biopsies. Seven biopsies showed a lower grade of rejection on follow-up biopsy, 4 biopsies showed more severe rejection, and 10 had unchanged grade. In only 9 of these 21 (43%) cases, did the interval serum amylase or lipase trend parallel the subsequent biopsy diagnosis. CONCLUSIONS: With a high biopsy discordance rate, our data suggest that renal allograft rejection is a poor surrogate for pancreas allograft status. Likewise, serum amylase and lipase levels do not predict response to rejection therapy. Surveillance or posttherapy pancreas allograft biopsies may be a useful means to monitor pancreas allograft status.

Late steroid withdrawal and cardiovascular events in kidney transplant recipients.

INTRODUCTION: Cardiovascular events (CVE) are the leading cause of mortality in kidney transplant recipients. The adverse effects of long-term therapy with steroids on cardiovascular risk have motivated increasing interest in steroid withdrawal (SW). The objective of this study was to compare the incidences of CVE and all-cause mortality between patients who had undergone SW at 1 year posttransplant and control patients who continued on steroids. METHODS: A cohort of 400 consecutive adult recipients of a kidney transplant between 1993 and 1998 who qualified for late SW was studied. At 1 year posttransplant 188 patients underwent SW, whereas 212 patients continued on steroids. Cox proportional-hazards analysis was used to estimate CVE (cardiac and cerebrovascular events) and all-cause mortality hazard ratios (HR) for patients who had undergone SW versus controls who continued on steroids beyond 1 year. RESULTS: The average follow-up was 61 months. There were 44 (11%) cardiac events, 18 (4.5%) cerebrovascular events, and 41 deaths (10.3%). The composite outcome of CVE and all-cause mortality was reached in 26 (13.8%) subjects who had undergone SW and 50 (23.6%) controls (P=0.013). In adjusted analyses, SW was associated with decreased risk for the composite outcome (HR 0.46, 95% confidence interval [CI] 0.28-0.76), cardiac events (HR 0.48, 95% CI 0.28-0.84), and all-cause mortality (HR 0.27, 95% CI 0.12-0.59). There was no association of SW with the risk for cerebrovascular events (HR 1.76, 95% CI 0.45-7.01). CONCLUSION: In this retrospective analysis, SW at 1 year posttransplant was associated with decreased risk for future CVE and all-cause mortality.

Long-term kidney regraft survival from deceased donors: risk factors and outcomes in a single center.

BACKGROUND: Although survival of kidney regrafts is similar to that of primary grafts, risk factors associated with regraft survival have not been defined clearly. The aim of this study was to investigate risk factors for regraft outcome, including characteristics of the previous and current transplant, and time to retransplant. METHODS: In a historical cohort study, 966 primary and 176 repeat deceased donor kidney graft recipients transplanted between January 1, 1990 and December 31, 2004 were studied. Cox regression analysis was used to estimate graft loss hazard ratios (HR) for regrafts versus primary grafts. Adjustments were made for recipient and donor demographics, transplant-related factors (transplant era, panel reactive antibodies, human leukocyte antigens mismatches, immunosuppression, delayed graft function, acute rejection [AR]), previous transplant characteristics (graft survival, graft loss because of AR), and time to retransplant. RESULTS: A total of 508 kidney grafts were lost in the period between January 1990 and May 2007: 427 primary grafts and 81 regrafts. Regraft recipients had a covariate-adjusted 6% increase in graft loss (HR=1.06; P=0.69). Regraft loss was significantly associated with previous graft survival less than or equal to 1 year (HR=2.01; P=0.004), previous graft loss because of AR (HR=2.26; P=0.017) and time to retransplant more than 1 year (HR=2.42; P=0.002). Other significant predictors of regraft loss were diabetes (HR=1.81), donor age more than 50 years (HR=1.86) and delayed graft function after retransplant (HR=1.95). CONCLUSIONS: Kidney regrafts seem to have similar long-term outcome as primary grafts. However, additional risk factors significantly associated with regraft survival are previous graft survival, graft loss because of rejection, and time to retransplant.

Two years postconversion from a prograf-based regimen to a once-daily tacrolimus extended-release formulation in stable kidney transplant recipients.

Tacrolimus extended-release (XL) is a once-daily formulation recently developed to reduce the frequency of dosing for patients currently using the twice-a-day formulation of tacrolimus (TAC). As reported previously, 67 kidney transplant recipients were safely converted (1:1 mg basis, total daily dose) from TAC twice-a-day to XL once-daily in the morning and were maintained on an am dosing regimen of XL using the same therapeutic monitoring and patient care techniques currently employed with TAC. The 2-year postconversion patient (100%) and graft (98.5%) survival, incidence of biopsy-confirmed acute rejection (6.0%), incidence of multiple rejections (1.5%), and safety profile (posttransplant diabetes, hyperlipidemia, hypertension, infections, renal dysfunction, hepatic dysfunction, and malignancies) were consistent with or more favorable than those previously reported for TAC twice-a-day.

Strategies to increase living donor kidney transplants.

There is an insufficient supply of deceased donor kidneys for transplantation. One solution is to increase the number of living donor kidney transplants. Our kidney transplant database was reviewed for 3 periods of 12 months each, separated by 5 years, to show the trends in kidney transplant donor sources and the influence of biologically unrelated living renal donors, minimally invasive living renal donor surgery, transplantation of ABO-incompatible kidneys from living donors, and transplantation in spite of positive cross-matches on the numbers of renal transplants and 1-year kidney transplant survival rates at our center. When results for 1993 were compared with 2003, the annual number of living donor renal transplants increased from 25 to 86, and the annual number of deceased donor renal transplants decreased from 108 to 63. The total number of kidney transplants increased by 12%. However, 1-year living donor kidney transplant survivals were not significantly different (94% for transplants done in 1993 vs 98% for transplants done in 2003). The strategies of living donor renal transplants from genetically unrelated donors, ABO-incompatible donors, and cross-match positive donors as well as the introduction of hand-assisted laparoscopic donor nephrectomy increased the number of living renal donor renal transplants at our center without compromising short-term kidney transplant survival rates.