HLA matching for kidney transplantation

Egg donation and gestational surrogacy: Pregnancy is riskier with an unrelated embryo

Modern medicine has revolutionized family planning. Remarkably, women1 can carry to term embryos with whom they share no genetic connection, a feat made possible through egg donation and/or gestational surrogacy. Our reproductive systems evolved to accommodate embryos that are 50% related to the carrier, not 0% related. Here, we apply evolutionary theory to explain how and why pregnancy is riskier with an unrelated embryo. When a woman gestates an unrelated embryo, she is significantly more likely to develop preeclampsia and other diseases above and beyond the known risks associated with advanced maternal age, IVF, multiple gestation, and subfertility. Such "allogeneic pregnancies" are riskier even in fertile, healthy, commercial surrogates and when the egg is donated by a young, healthy donor. We propose that unrelated embryos present a special immune challenge to the gestational carrier, because they have fewer matching genes to the maternal body-therefore exacerbating symptoms of evolutionary maternal-fetal conflict. Indeed, maternal risks seem lower when the embryo is more related to the carrier, e.g., if a sister donates the egg. Finally, we discuss microchimerism in egg donation pregnancies, whereby wholly foreign cells pass from mother to embryo and vice-versa. We conclude with several medical proposals. First, egg donors and surrogates should be informed of the increased health risks they would face. In considerations of risk, these young, fertile women should not be compared to older, infertile women undergoing IVF; the proper comparison group is other young, fertile women. Second, contrary to some medical advice, perhaps genetically-related egg donors and surrogates should be preferred, all else equal. An immunological matching scheme, like what is used for organ transplants, could improve surrogate pregnancy outcomes. Third, more research is needed on microchimerism, sperm exposure, and the long-term impacts of allogeneic pregnancies on maternal and child health.

HLA class-I polymorphisms among the Punjabi population of Pakistan: A comparative analysis with country's other ethnic groups

The Punjabi population, constituting over 45 % of the country's total population, holds the highest prevalence in Pakistan. To understand their HLA genetics, we genotyped 389 Punjabi subjects for major Class-I loci using the PCR-SSO Luminex® method. Our study identified a total of 162 alleles, including 41 different HLA-A, 72 HLA-B, and 49 HLA-C alleles. The most common alleles included A*11:01 (14.6 %), A*01:01 (11.8 %), A*24:02 (11.3 %); B*40:06 (13.3 %), B*08:01 (10.9 %), B*51:01 (8.7 %); C*15:02 (15.5 %), C*07:02 (15.3 %), and C*04:01 (10.8 %). However, only locus B showed a significant deviation from HWE. The dominant Class I haplotype was A*24:02-B*40:06-C*15:02, followed by A*11:01-B*40:06-C*15:02, while significant LD was observed between all pairs of HLA loci. A distinct genetic makeup was observed in the Pakistani Punjabis as compared to Indian Punjabis, emphasizing the impact of the Indo-Pak partition and religious choices for marriage. In comparison to country's other ethnic groups, the Pakistani population exhibited 76 different alleles at a low field-resolution, with the Punjabi population having highest polymorphism. Phylogenetic analysis revealed that the Punjabi population is most closely related to the Sindhi population, while both populations sharing ancient connections with the Burusho population. These findings have significant implications for transplantation procedures, personalized medicine, disease susceptibility, and evolutionary studies.

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.

HLA molecular study of patients in a public kidney transplant program in Guatemala

Guatemala is a country located in Central America, and while it is one of the most populated countries in the region, the genetic diversity of the population has been poorly analyzed. Currently, there are no analyses of the distribution of human leukocyte antigen (HLA) system alleles in mixed ancestry (i.e., ladino) populations in Guatemala. The HLA system exhibits the most extensive polymorphism in the human genome and has been extensively analyzed in a large number of studies related to disease association, transplantation, and population genetics (with particular importance in the understanding of diversity in the human population). Here, we present HLA typing data from 127 samples of unrelated individuals from the kidney transplant program of the San Juan de Dios General Hospital (Guatemala City) using a PCR-SSOP-based (PCR-sequence specific oligonucleotide probes) typing method. We found 16 haplotypes that accounted for 39.76 % of the total haplotype diversity, of which thirteen have been reported previously in Native American populations and three have been reported in European populations. The analyses showed no deviations from Hardy-Weinberg equilibrium, and admixture estimates calculated with k = 3 ancestral components showed that Native American was the most represented component, followed by the European component. The African component was less prominent in the Guatemala mixed ancestry sample in comparison to samples from other countries in Central America. The HLA-based admixture results for Central America showed a continuum in the distribution of Native American, European and African ancestries throughout the region, which is consistent with the complex demographic history of the region.

A Retrospective Study on Human Leukocyte Antigen Types and Haplotypes in a South African Population

CONTEXT.—

Human leukocyte antigen (HLA) is a polymorphic protein of the immune system with a central role in organ transplantation. Organ recipients can be sensitized against HLA from previous exposure, which increases the likelihood of antidonor immune responses and subsequently organ rejection. HLA matching represents an attractive option to improve graft function, reduce sensitization of recipients in first transplantations, and improve organ allocation.

OBJECTIVE.—

To examine the feasibility of the reintroduction of HLA matching into the criteria in the Johannesburg program, we retrospectively assessed HLA types in our donor population.

DESIGN.—

HLA types of 782 deceased and related living donors from 2015 until 2019 were recorded and analyzed to identify the most common HLA types and haplotypes. A virtual crossmatch was also done to examine the anti-HLA antibodies in the recipient population compared with the common HLA types identified in this study.

RESULTS.—

Of the most common HLA types identified, at least 1 was present in 732 (93.6%) of the renal donors assessed. The virtual crossmatch confirmed that most recipients are sensitized against most donors, and this greatly impacts the number of recipients who can receive organ transplants.

CONCLUSIONS.—

This study determined the most common HLA types and haplotypes in a South African organ donor population. This information, combined with the evidence suggesting the immunogenic potential of these common types, the high number of recipients with antibodies against common HLA types, and the ethnic distribution of the donor and recipient populations, informs the recommendation that the pretransplantation workup should not reinclude HLA matching.

Human Leukocyte Antigen Examination Using Luminex®-Based Assays for Donor-Recipient Compatibility Assessment in Kidney Transplantation: Our Preliminary Experience

Background: Detection of anti-HLA antibodies (HLAabs) in organ transplantation recipients is vital to determine whether the recipient has specific HLAabs against the donor’s HLA molecules (donor-specific anti-HLA antibodies [DSA]). Methods: This preliminary study involved seven subjects: five without prior HLA sensitization and two with a history of possible HLA sensitization (kidney transplantation and pregnancy). Two of the subjects were siblings, two of the subjects were mother and son, and two of them were first cousins once removed. All the subjects underwent HLA typing, and four of the subjects underwent HLAabs assays using the sequence-specific oligonucleotide probes (SSOP) method. Results: There were 10/16 HLA matches between subjects who were siblings and between subjects who were mother and son, and 6/16 HLA matches were found between subjects who were first cousins once removed. Subjects with previous kidney transplantation developed 59 HLA-Abs toward class I and class II HLA (the mean fluorescence intensity (MFI) value range: 1,003.36 to 12,404.77). HLAabs were also found among subjects without prior HLA sensitization, albeit with relatively lower MFI values. Conclusions: HLA typing and HLAabs detection for donor-recipient compatibility assessment using the SSOP method offers more detailed, semi-quantitative results. Further research involving larger subjects in cohort settings will be useful for profiling MFI cut-off values for HLAabs.

The role of HLA-DP mismatches and donor specific HLA-DP antibodies in kidney transplantation: a case series

BACKGROUND

The impact of HLA-DP mismatches on renal allograft outcome is still poorly understood and is suggested to be less than that of the other HLA loci. The common association of HLA-DP donor-specific antibodies (DSA) with other DSA obviates the evaluation of the actual effect of HLA-DP DSA.

METHODS

From a large multicenter data collection, we retrospectively evaluated the significance of HLA-DP DSA on transplant outcome and the immunogenicity of HLA-DP eplet mismatches with respect to the induction of HLA-DP DSA. Furthermore, we evaluated the association between the MFI of HLA-DP antibodies detected in Luminex assays and the outcome of flowcytometric/complement-dependent cytotoxicity (CDC) crossmatches.

RESULTS

In patients with isolated pretransplant HLA-DP antibodies (N = 13), 6 experienced antibody-mediated rejection (AMR) and 3 patients lost their graft. In HLAMatchmaker analysis of HLA-DP mismatches (N = 72), HLA-DP DSA developed after cessation of immunosuppression in all cases with 84DEAV (N = 14), in 86% of cases with 85GPM (N = 6/7), in 50% of cases with 56E (N = 6/12) and in 40% of cases with 56A mismatch (N = 2/5). Correlation analysis between isolated HLA-DP DSA MFI and crossmatches (N = 90) showed negative crossmatch results with HLA-DP DSA MFI <2000 (N = 14). Below an MFI of 10,000 CDC crossmatches were also negative (N = 33). Above these MFI values both positive (N = 35) and negative (N = 16) crossmatch results were generated.

CONCLUSIONS

Isolated HLA-DP DSA are rare, yet constitute a significant risk for AMR. We identified high-risk eplet mismatches that can lead to HLA-DP DSA formation. We therefore recommend HLA-DP typing to perform HLA-DP DSA analysis before transplantation. HLA-DP DSA with high MFI were not always correlated with positive crossmatch results.

A single center study of protective and susceptible HLA alleles and haplotypes with end-stage renal disease in China

Chronic kidney disease (CKD) is becoming a global public health problem and usually cause End-Stage Renal Disease (ESRD) in the end of progression. To analyze the associations of HLA-A, -B, -C, -DRB1 and -DQB1 alleles at high resolution with ESRD in Jiangsu province of China, a total of 499 unrelated patients with ESRD from the First Affiliated Hospital with Nanjing Medical University and 1584 healthy controls from Jiangsu Branch of Chinese Marrow Donor Program (CMDP) were genotyped at HLA-A, -B, -C, -DRB1 and -DQB1 loci. Statistical analysis was applied to compare the differences of HLA allele frequencies between patients with ESRD and healthy controls. As results, no protective allele at A locus was found and the susceptible alleles were A*11:01 and A*31:01. At B locus, B*15:01, B*55:02 and B*39:05 emerged as susceptible alleles, whereas no protective allele was found. At C locus, C*06:02 and C*07:01 emerged as protective alleles and no susceptible allele was found. At DRB1 locus, six alleles including DRB1*03:01, DRB1*04:03, DRB1*04:04, DRB1*04:05, DRB1*11:01 and DRB1*12:02 emerged as susceptible alleles, while DRB1*15:01 emerged as a protective allele. At DQB1 locus, DQB1*02:01, DQB1*03:01, DQB1*03:02 and DQB1*04:01 emerged as susceptible alleles, while DQB1*06:02 and DQB1*06:09 emerged as protective alleles. Haplotype A*11:01-C*03:03-B*15:01-DRB1*11:01-DQB1*03:01 containing four susceptible alleles was regarded as the most susceptible haplotype. The susceptible alleles and haplotypes might be used as some important risk classification markers. Besides, in the consanguineous renal transplantation, it would be very beneficial for the long-term survival of renal transplant patients to avoid the susceptible alleles and haplotypes in selecting optimal donors.

Association of Human Leukocyte Antigen Haplotypes With End-Stage Renal Disease in Vietnamese Patients Prior to First Transplantation

INTRODUCTION

The prevalence of chronic kidney failure is significantly increasing in Vietnam, causing a burden for health care. This study assessed the relationship of HLA-A, -B, and -DRB1 alleles with end-stage renal disease (ESRD).

METHOD

A retrospective, cross-sectional study and a comparative study using secondary data analysis were conducted on 196 ESRD patients and 187 controls from 2009 to 2017. The patient and donor profiles were collected from medical records, including age, sex, etiology of renal failure, and HLA phenotypes. HLA-A*, -B*, and -DRB1* typing were done by polymerase chain reaction-sequence specific primers.

RESULT

The most frequent HLA alleles in Vietnamese patients with ESRD were HLA-A*02, -A*11, -B*15, -B*46, -DRB1*04, -DRB1*09, and -DRB1*12. The haplotypes HLA-A*0233 (odds ratio [OR] = 0.40, 95% CI: 0.15-0.98) had a negative association for ESRD. The haplotypes HLA-B*1515 (OR = 4.14, 95% CI: 1.52-11.26) and HLA-DRB1*1212 (OR = 2.01, 95% CI: 1.06-3.81) had a positive association for ESRD. The haplotypes HLA-B*1515 (OR = 4.69, 95% CI: 1.69-13.03) and -DRB1*1212 (OR = 2.15, 95% CI: 1.10-4.21) had a positive association for ESRD related to glomerulonephritis. The HLA-B*1557 (OR = 17.34, 95% CI: 2.70-11.49) had a positive association for ESRD related to hypertension.

CONCLUSION

The haplotypes of HLA class I and II had significant relationships with ESRD. The results of our study should be confirmed in further investigations.

Optimizing PLG nanoparticle-peptide delivery platforms for transplantation tolerance using an allogeneic skin transplant model

A robust regimen for inducing allogeneic transplantation tolerance involves pre-emptive recipient treatment with donor splenocytes (SP) rendered apoptotic by 1-ethyl-3-(3'-dimethylaminopropyl)-carbodiimide(ECDI) treatment. However, such a regimen is limited by availability of donor cells, cost of cell procurement, and regulatory hurdles associated with cell-based therapies. Nanoparticles (NP) delivering donor antigens are a promising alternative for promoting transplantation tolerance. Here, we used a B6.C-H-2^bm12(bm12) to C57BL/6(B6) skin transplant model involving a defined major histocompatibility antigen mismatch to investigate design parameters of poly(lactide-co-glycolide) (PLG) NPs delivering peptides containing the donor antigen for optimizing skin allograft survival. We showed that an epitope-containing short peptide (P1) was more effective than a longer peptide (P2) at providing graft protection. Importantly, the NP and P1 complex (NP-ECDI-P1) resulted in a significant expansion of graft-infiltrating Tregs. Interestingly, in comparison to donor ECDI-SP that provided indefinite graft protection, NP-ECDI-P1 targeted different splenic phagocytes and skin allografts in these recipients harbored significantly more graft-infiltrating CD8⁺IFN-γ⁺ cells. Collectively, the current study provides initial engineering parameters for a cell-free and biocompatible NP-peptide platform for transplant immunoregulation. Moreover, it also provides guidance to future NP engineering endeavors to recapitulate the effects of donor ECDI-SP as a goal for maximizing tolerance efficacy of NP formulations.

Web-Based Tailored Intervention to Support Optimal Medication Adherence Among Kidney Transplant Recipients: Pilot Parallel-Group Randomized Controlled Trial

Background

Optimal immunosuppressive medication adherence is essential to graft survival. Transplant-TAVIE is a Web-based tailored intervention developed to promote this adherence.

Objective

The objective of our study was to evaluate the Transplant-TAVIE intervention’s acceptability, feasibility, and preliminary efficacy.

Methods

In a pilot, parallel-group, randomized controlled trial, we randomly assigned a convenience sample of 70 kidney transplant patients on immunosuppressive medication either to an experimental group (Transplant-TAVIE) or to a control group (existing websites). Kidney transplant recipients had to be older than 18 years, be taking immunosuppressant medication, and have access to the internet to participate in this study. Transplant-TAVIE was composed of three interactive Web-based sessions hosted by a virtual nurse. We documented user appreciation of and exposure to the intervention. Furthermore, we assessed medication adherence, medication self-efficacy, intake-related skills, and medication side effects at baseline and 3 and 6 months later. Analyses of variance were used to assess intergroup differences over time.

Results

After baseline questionnaire completion, participants were randomly assigned either to Transplant-TAVIE (n=35) or to the websites (n=35) group. All participants had received their kidney graft <1 year to 32 years earlier (mean 6.8 years). Of the experimental group, 54% (19/35) completed the sessions of Transplant-TAVIE. Users found the intervention to be acceptable—33% were extremely satisfied (6/18), 39% were very satisfied (7/18), and 28% were satisfied (5/18). At baseline and over time, both experimental and control groups reported high medication adherence, high medication self-efficacy, and frequent use of skills related to medication intake. No intergroup differences emerged over time.

Conclusions

The results of this study support the feasibility and acceptability of Transplant-TAVIE. It could constitute an accessible adjunct in support of existing specialized services.

The clinical significance of epitope mismatch load in kidney transplantation: A multicentre study

Since the advent of kidney transplantation a key strategy for maximising graft survival by avoiding allorecognition has been to minimise HLA mismatching between donor and recipient. As HLA antibodies are now recognised as being specific for epitopes and donor-recipient HLA mismatch at the amino acid level can now be determined, HLA epitope mismatch load could be a better predictor for dnDSA development than classical HLA antigen mismatch calculation. This hypothesis has been investigated by other studies and the aim of our multicentre study was to confirm this observation in our population. Two algorithms, HLAMatchmaker and PIRCHE-II, were used to determine the HLA epitope mismatch load between donor and recipient. We have shown a significant association between the number of HLA epitope mismatches and the development of dnDSA and we have confirmed the earlier observations.

Genome-wide association studies in kidney transplantation: Advantages and constraints

Since the discovery of the human leukocyte antigen (HLA) system, the role of HLA molecules in the field of transplantation has been appreciated: better matching leads to better graft function. Since then, the association of other genetic polymorphisms with clinical outcome has been investigated in many studies. Genome-wide association studies (GWAS) represent a powerful tool to identify causal genetic variants, by simultaneously analyzing millions of single nucleotide polymorphisms scattered across the genome. GWAS in transplantation may indeed be useful to reveal novel markers that may potentially be involved in the mechanism of allograft rejection and graft failure. However, the relevance of GWAS for risk stratification or donor selection for an individual patient is limited as is already reflected by the fact that many parameters, significant in one study, cannot be confirmed in another one.

The Privilege of Induction Avoidance and Calcineurin Inhibitors Withdrawal in 2 Haplotype HLA Matched White Kidney Transplantation

Background

White recipients of 2-haplotype HLA-matched living kidney transplants are perceived to be of low immunologic risk. Little is known about the safety of induction avoidance and calcineurin inhibitor withdrawal in these patients.

Methods

We reviewed our experience at a single center and compared it to Organ Procurement and Transplantation Network (OPTN) registry data and only included 2-haplotype HLA-matched white living kidney transplants recipients between 2000 and 2013.

Results

There were 56 recipients in a single center (where no induction was given) and 2976 recipients in the OPTN. Among the OPTN recipients, 1285 received no induction, 903 basiliximab, 608 thymoglobulin, and 180 alemtuzumab. First-year acute rejection rates were similar after induction-free transplantation among the center and induced groups nationally. Compared with induction-free transplantation in the national data, there was no decrease in graft failure risk over 13 years with use of basiliximab (adjusted hazard ratio [aHR], 0.86; confidence interval [CI], 0.68-1.08), Thymoglobulin (aHR, 0.92; CI, 0.7-1.21) or alemtuzumab (aHR, 1.18; CI, 0.72-1.93). Among induction-free recipients at the center, calcineurin inhibitor withdrawal at 1 year (n = 27) did not significantly impact graft failure risk (HR,1.62; CI, 0.38-6.89).

Conclusions

This study may serve as a foundation for further studies to provide personalized, tailored, immunosuppression for this very low-risk population of kidney transplant patients.

Thirty Years of Experience at the First Tunisian Kidney Transplant Center

OBJECTIVES

The aim of this study was to report the results of 30 years of experience at the first kidney transplant center in Tunisia.

MATERIALS AND METHODS

All kidney transplants performed at the center between June 1986 and June 2016 were included. The study period was divided into 3 decades. Recipient and donor data and follow-up information were obtained from a local database and patient medical records. Comparative analyses were performed using the t test for continuous variables and the Χ² test for qualitative variables. Patient and graft survival rates were calculated according to the actuarial method, and comparison of survival curves was performed according to the logrank test.

RESULTS

The mean age of recipients was 32.7 ± 11.5 years (range, 6-65 y) with a gender ratio of 2.2. Duration of prekidney transplant dialysis varied from 2 months to 20 years (median, 27.5 mo); 1.7% of patients underwent transplant preemptively. Kidneys were recovered from deceased donors in 21.2% of cases and from living donors in 78.8%. The proportion of deceased donors dropped from 27.4% during the period 2006-2010 to 12.9% during the period 2011-2015 (P < .04). Patient survival rates at 1, 5, 10, 15, and 20 years were 96%, 89.3%, 79.5%, 71.1%, and 65.4%. Graft survival rates were 95%, 86.5%, 76.2%, 66.3%, and 57.2%. The annual graft loss was 2.9%, with a mortality rate of 2.4% and without significant differences between patients receiving deceased-donor and living-donor organs.

CONCLUSIONS

Kidney transplant activity remains suboptimal in our country. The reduction in deceased-donor organs could be related to the political transformations facing our country with their resulting social and economic consequences. Efforts should be made to increase governmental resources and to improve both public awareness of organ donation and the motivation of transplant teams.

Role of Human Leukocyte Antigen Compatibility in Graft Outcomes After Living Donor Liver Transplantation

PURPOSE

The influence of human leukocyte antigen (HLA) mismatch on liver transplantation has been widely studied, but is still controversial. The aim of this large single-center study was to analyze the role of HLA compatibility between donor and recipient in the graft outcomes of living donor liver transplantation (LDLT).

MATERIALS AND METHODS

A total of 925 recipients who had undergone LDLT between March 2001 and April 2012 were retrospectively analyzed. HLA typing was performed using a standard complement-dependent cytotoxicity technique. The degree and type of HLA-A, HLA-B, and HLA-DR mismatch were assessed. We also investigated the posttransplantation laboratory data, incidence of rejection, recurrence of hepatitis B virus (HBV), and graft survival as outcome parameters.

RESULTS

The type of HLA-A, HLA-B, and HLA-DR mismatch had no effect on rejection episodes, whereas the beneficial effect of a much lower degree (0-2) of HLA mismatch was notable. Recipients with 2 HLA-B mismatches or recipients with a higher degree of mismatch were associated with elevated bilirubin level, a higher recurrence rate of HBV, and inferior graft survival. A complete mismatch of 2 at the DR locus also decreased graft survival in LDLT recipients.

CONCLUSIONS

This study confirmed that the degree of HLA mismatch, as well as the locus-specific type of HLA mismatch, namely B and DR, play a major role in graft outcomes after LDLT. To obtain an improved graft outcome, HLA compatibility should be considered in the setting of LDLT, which provides sufficient time to select a more favorable donor-recipient combination.

[Immunological monitoring in kidney transplantation: 13 years experience of a Moroccan histocompatibility laboratory]

PURPOSE OF STUDY

The quality of the immunological monitoring is crucial because it determines the success of the kidney transplantation. The scope of this work is to describe the experience of the department of immunological unity of the Ibn Sina university hospital in Rabat regarding the immunological monitoring of patients transplanted between 2001 and 2014.

PATIENTS AND METHODS

Patient samples were collected from nephrology services of different public and private hospitals of Morocco. The tests conducted in the context of immunological monitoring are ABO typing, HLA-A, B, DR, DQ typing, anti-HLA antibodies detection and identification and cross-match.

RESULTS

One hundred and fourteen benefited from a pre- and post-transplant immunological monitoring in our laboratory. The percentage of recipients having between 2 and 5 stored sera is 60.5 before transplantation and 56.1 after transplantation. Immunized patients account for 22.8% before the transplant and 17.6% after transplantation. Ninety-seven patients still have a functional graft, while 4 of them had DSA of low intensity before transplantation. Five immunological rejections were reported while the cross-match were negative and no DSA was identified before transplantation. Patient survival and graft at 1 year was 98.2% and 92.7% respectively.

CONCLUSION

Conducting regular immunological monitoring is sometimes difficult in our context, however, the results are satisfactory in terms of graft and patients survival.

Emotional management and quality of life in mother living versus multi-organ donor renal transplant recipients

The aim of this study was to evaluate psychological differences and quality of life between kidney recipients from living (mother) and multi-organ donor. Overall, 40 patients who had undergone both living (mother) and multi-organ kidney transplantation 3-6 months before were asked to complete four self-report instruments: Toronto Alexithymia Scale, Short Form Health Survey, Regulatory Emotional Self-efficacy, and Attachment Style Questionnaire. A greater difficulty in emotional, social, and mental health functioning was found in recipients receiving kidney from mother living donor. Moreover, in these patients, higher levels of avoidant attachment dimensions were associated with a worse quality of life.

Transplanting the elderly: Balancing aging with histocompatibility

Across the world, the proportions of senior citizens (i.e. those ≥65years) increase rapidly and are predicted to constitute over 25% of the general population by 2050. In 2012 already 48% of the population with end stage renal disease (ESRD) was aged 65years or older. Transplantation is considered the preferred treatment option for ESRD offering survival advantage over long-term dialysis in the majority of patients. Indeed, acceptable outcomes have been documented for selected patients over the age of 70years or even cases over 80years. The reality of organ scarcity and prolonged waiting times for a deceased donor kidney transplantation, however, indicate that at best 50% of the selected elderly may have realistic expectations to receive a timely transplant offer. By choice or medical selection, access to transplantation also decreases with increasing age. In order to expedite the chance for elderly to receive a kidney transplant dedicated allocation systems have been developed. These allocation systems, like the Eurotransplant Senior Program (ESP), support preferential local allocation of kidneys from older donors to older patients in order to match recipient and graft life while disregarding histocompatibility for HLA antigens. The consequence has been more acute rejection episodes and an increase in immunosuppressive load. In the elderly, the most common cause of graft loss is death with functioning graft and death from infectious diseases is one of the dominant causes. The Eurotransplant Senior DR-compatible Program (ESDP) was designed to further improve the perspective of successful transplantation in the elderly in terms of life and quality of life by re-introducing matching criteria for HLA-DR in the old-for-old algorithm.

Clinical factors affecting rejection rates in liver transplantation

BACKGROUND

With improvements in survival, liver transplant recipients now suffer more morbidity from long-term immunosuppression. Considerations were given to develop individualized immunosuppression based on their risk of rejection.

METHOD

We retrospectively analyzed the data of 788 liver transplants performed during the period from October 1991 to December 2011 to study the relationship between acute cellular rejection (ACR) and various clinical factors.

RESULTS

Multivariate analysis showed that older age (P=0.04, OR=0.982), chronic hepatitis B virus infection (P=0.005, OR= 0.574), living donor liver transplantation (P=0.02, OR=0.648) and use of interleukin-2 receptor antagonist on induction (P<0.001, OR=0.401) were associated with fewer ACRs. Patients with fulminant liver failure (P=0.004, OR=4.05) were more likely to develop moderate to severe grade ACR.

CONCLUSIONS

Liver transplant recipients with older age, chronic hepatitis B virus infection, living donor liver transplantation and use of interleukin-2 receptor antagonist on induction have fewer ACR. Patients transplanted for fulminant liver failure are at higher risk of moderate to severe grade ACR. These results provide theoretical framework for developing individualized immunosuppression.

Methodological aspects of anti-human leukocyte antigen antibody analysis in solid organ transplantation

Donor human leukocyte antigen (HLA)-specific antibodies (DSA) play an important role in solid organ transplantation. Preexisting IgG isotype DSA are considered a risk factor for antibody mediated rejection, graft failure or graft loss. The post-transplant development of DSA depends on multiple factors including immunogenicity of mismatched antigens, HLA class II typing of the recipient, cytokine gene polymorphisms, and cellular immunoregulatory mechanisms. De novo developed antibodies require special attention because not all DSA have equal clinical significance. Therefore, it is important for transplant clinicians and transplant immunologists to accurately characterize DSA. In this review, the contemporary immunological techniques for detection and characterization of anti-HLA antibodies and their pitfalls are described.

HLA-E-restricted cross-recognition of allogeneic endothelial cells by CMV-associated CD8 T cells: a potential risk factor following transplantation

Although association between CMV infection and allograft rejection is well admitted, the precise mechanisms involved remain uncertain. Here, we report the characterization of an alloreactive HLA-E-restricted CD8 T cell population that was detected in the PBL of a kidney transplant patient after its CMV conversion. This monoclonal CD8 T cell population represents a sizable fraction in the blood (3% of PBL) and is characterized by an effector-memory phenotype and the expression of multiple NK receptors. Interestingly, these unconventional T cells display HLA-E-dependent reactivity against peptides derived from the leader sequences of both various HCMV-UL40 and allogeneic classical HLA-I molecules. Consequently, while HLA-E-restricted CD8 T cells have potential to contribute to the control of CMV infection in vivo, they may also directly mediate graft rejection through recognition of peptides derived from allogeneic HLA-I molecules on graft cells. Therefore, as HLA-E expression in nonlymphoid organs is mainly restricted to endothelial cells, we investigated the reactivity of this HLA-E-restricted T cell population towards allogeneic endothelial cells. We clearly demonstrated that CMV-associated HLA-E-restricted T cells efficiently recognized and killed allogeneic endothelial cells in vitro. Moreover, our data indicate that this alloreactivity is tightly regulated by NK receptors, especially by inhibitory KIR2DL2 that strongly prevents TCR-induced activation through recognition of HLA-C molecules. Hence, a better evaluation of the role of CMV-associated HLA-E-restricted T cells in transplantation and of the impact of HLA-genotype, especially HLA-C, on their alloreactivity may determine whether they indeed represent a risk factor following organ transplantation.

Effect of donor and recipient variables on the long-term live-donor renal allograft survival in children

Objective

We aimed to analyse donor and recipient predictors of graft survival in children who received live-donor renal grafts.

Patients and methods

The study comprised 273 children who received live-donor renal transplants at our center between March 1976 and October 2010. The follow-up ranged from 6 months to 25 years. Donor variables included donor age, gender, donor/recipient body weight ratio (DR BWR), ABO blood groups, human leukocyte antigen, and DR mismatching. Donor-specific problems, e.g., ischemia time during surgery and number of renal arteries, were included. Recipient variables included recipient age, sex, original kidney disease, ischemia time, acute tubular necrosis (ATN) after transplantation, immunosuppression, number of acute rejection episodes, re-transplantation, and development of hypertension.

Results

Independent variables with a sustained effect on the 5- and 10-year graft survival on multivariate analysis were: ATN after transplant, number of acute rejections, hypertension, and DR BWR. At the last follow-up, 185 patients (67.8%) had a functioning graft, while 82 (30.0%) had graft failure. Only six patients (0.02%) were lost to follow-up.

Conclusion

Donor and recipient variables that affect short- and long-term graft survival in children with a live-donor renal allograft are DR BWR, number of acute rejections, ATN and hypertension after transplant. Considering these variables provides a better outcome.

Urinary soluble HLA-DR is a potential biomarker for acute renal transplant rejection

BACKGROUND.: Urine is a potentially rich source of biomarkers for monitoring kidney dysfunction. In this study, we have investigated the potential of soluble human leukocyte antigen (sHLA)-DR in the urine for noninvasive monitoring of renal transplant patients. METHODS.: Urinary soluble HLA-DR levels were measured by sandwich enzyme-linked immunosorbent assay in 103 patients with renal diseases or after renal transplantation. sHLA-DR in urine was characterized by Western blotting and mass spectrometry. RESULTS.: Acute graft rejection was associated with a significantly elevated level of urinary sHLA-DR (P<0.0001), compared with recipients with stable graft function or healthy individuals. A receiver operating characteristic curve analysis showed the area under the curve to be 0.88 (P<0.001). At a selected threshold, the sensitivity was 80% and specificity was 98% for detection of acute renal transplant rejection. sHLA-DR was not exosomally associated and was of lower molecular weight compared with the HLA-DR expressed as heterodimer on the plasma membrane of antigen-presenting cells. CONCLUSIONS.: sHLA-DR excreted into urine is a promising indicator of renal transplant rejection.

The influence of class II transactivator and interleukin-6 polymorphisms on the production of antibodies to donor human leucocyte antigen mismatches in renal allograft recipients

The influence of polymorphisms in the CIITA and IL-6 genes on donor-specific human leucocyte antigen antibody production was investigated in a cohort of renal transplant recipients and their donors. CIITA and IL-6 single nucleotide polymorphisms were found to be associated with donor-specific human leucocyte antigen antibody production post-transplantation.

Association of genetic variation in inducible costimulator gene with outcome of kidney transplantation

BACKGROUND

The closely-linked genes of CD28, cytotoxic T-lymphocyte associated antigen 4 (CTLA4), inducible costimulator (ICOS), and programmed cell death 1 on chromosome 2q encode costimulatory molecules, which are regulators of the T-cell activity. The T-cell mediated immune response has a major role in allograft rejection. Hence, the variation in these genes may have an effect on graft survival and the amount of immunosuppression needed, but so far the studies have restricted solely to the CTLA4 gene.

METHODS

We determined 13 single nucleotide polymorphisms in CD28, CTLA4, ICOS, and PPCD1 genes in 678 adult patients who received a kidney from deceased donor. The effect of genetic variation on the outcome of renal transplantation was analyzed.

RESULTS

Two markers on the ICOS gene, rs10183087 and rs4404254, were associated with delayed graft function (odds ratio=5.8; P=0.020 and odds ratio=5.8; P=0.019, respectively). Interestingly, the same ICOS variation has been shown to regulate the expression level of ICOS. We also demonstrated an association of the ICOS polymorphism rs10932037 with the graft survival (P=0.026).

CONCLUSIONS

The present results indicate that potentially functional genetic variation in T-cell costimulatory molecule ICOS has an effect on the outcome of kidney transplantation.

Is matching for human leukocyte antigen-DR beneficial in pediatric kidney transplantation?

This Practice Point commentary discusses the findings and limitations of a report by Gritsch et al., in which the authors concluded that human leukocyte antigen (HLA)-DR-mismatched kidneys from deceased donors aged 35 years or less are suitable for use in pediatric patients. We highlight the issues to be considered before adopting such an allocation policy. Gritsch et al. reported that the 5-year survival rates of grafts with zero HLA-DR mismatches were identical to those of grafts that were completely mismatched for HLA-DR; however, the report did not provide information about the immunosuppressive regimens used or the frequency of rejection episodes and their treatment. Children who receive HLA-DR-mismatched kidneys will ultimately be exposed to more-intensive immunosuppression in order to overcome the potentially increased risks of acute rejection, graft failure and sensitization. In spite of recent improvements in immunosuppressive therapy, we believe that HLA matching remains crucial for the survival of kidney transplants.

Induction of transplantation tolerance by combining non-myeloablative conditioning with delivery of alloantigen by T cells

The observation that bone marrow derived hematopoietic cells are potent inducers of tolerance has generated interest in trying to establish transplantation tolerance by inducing a state of hematopoietic chimerism through allogeneic bone marrow transplantation. However, this approach is associated with serious complications that limit its utility for tolerance induction. Here we describe the development of a novel approach that allows for tolerance induction without the need for an allogeneic bone marrow transplant by combining non-myeloablative host conditioning with delivery of donor alloantigen by adoptively transferred T cells. CBA/Ca mice were administered 2.5 Gy whole body irradiation (WBI). The following day the mice received K(b) disparate T cells from MHC class I transgenic CBK donor mice, as well as rapamycin on days 0-13 and anti-CD40L monoclonal antibody on days 0-5, 8, 11 and 14 relative to T cell transfer. Mice treated using this approach were rendered specifically tolerant to CBK skin allografts through a mechanism involving central and peripheral deletion of alloreactive T cells. These data suggest robust tolerance can be established without the need for bone marrow transplantation using clinically relevant non-myeloablative conditioning combined with antigen delivery by T cells.

A retrospective analysis of immunosuppression compliance, dose reduction and discontinuation in kidney transplant recipients

We describe factors associated with poor compliance and dose reductions and examine the relative impact of compliance, dose reduction and discontinuation on graft outcome. Medicare claims for MMF in 7062 deceased donor renal recipients with at least 1 year of graft function were used to calculate compliance and dose reductions. Compliance was modeled using medication possession ratio to define quartiles for poor, low, medium and high compliance. The relative impact of compliance, dose reduction and discontinuation on graft outcome was assessed with Cox proportional hazards. Pediatric (Age 0-18, Odds ratio = 1.71, 95% CI 1.11-2.63, p = 0.014) and adolescent recipients (19-24, 1.57, 1.23-2.00, p < 0.001) were more likely poorly compliant compared to adults age 25-44. Poor compliance was also associated with physical limitations, hypertension, delayed graft function, rejection, infection and GI conditions. Poor (1.43, 1.11-1.84, p = 0.005) and low (1.46, 1.13-1.88, p = 0.004) compliance was associated with an increased hazard of graft loss as was >50% dose reduction (1.69, 1.15-2.50, p = 0.008) and discontinuation (8.34, 6.85-10.2, p < 0.001). Medication possession ratios lower than the 3-year mean were associated with an increased risk of graft loss. These results may indicate that interventions to improve compliance among kidney transplant recipients should strive for high rather than discourage low compliance.

Heme oxygenase 1 gene polymorphisms and outcome of renal transplantation

Heme oxygenase isoenzyme HO-1 has been linked to several cytoprotective functions with a potentially beneficial role in transplantation. In the present study, the effect of genetic variation in HO-1 on renal allograft outcome was investigated. Six hundred and eighty patients subject to renal transplantation in a single transplant unit and their cadaveric kidney donors were included in this study. Four single-nucleotide polymorphisms and one microsatellite marker in the HO-1 gene region were analysed. Some statistically nominally significant associations were observed in preliminary analyses between polymorphisms studied and clinical outcomes, but after correction for multiple comparisons none remained significant. Our data suggest that the HO-1 gene polymorphisms studied have no significant role on outcome of kidney transplantation in the Finnish population.

Chronic Allograft Nephropathy

Chronic allograft nephropathy (CAN) remains the Achilles heel of renal transplantation. In spite of the significant strides achieved in one-year renal allograft survival with newer immunosuppressant strategies, the fate of long-term renal allograft survival remains unchanged. The number of renal transplant recipients returning to dialysis has doubled in the past decade. This is especially important since these patients pose a significantly increased likelihood of dying while on the waiting list for retransplantation, due to increasing disparity between donor organ availability versus demand and longer waiting time secondary to heightened immunologic sensitization from their prior transplants. In this review we analyze the latest literature in detail and discuss the definition, natural history, pathophysiology, alloantigen dependent and independent factors that play a crucial role in CAN and the potential newer therapeutic targets on the horizon. This article highlights the importance of early identification and careful management of all the potential contributing factors with particular emphasis on prevention rather than cure of CAN as the core management strategy.

The impact of human leukocyte antigen matching on transplant complications and immunosuppression dosage

Administrative claims data facilitate ascertainment of outcomes not collected by the transplant registry and provide the opportunity to examine prescribed doses of immunosuppressive medications. Here, we examine the impact of human leukocyte antigen (HLA) matching on traditional outcomes, rejection and survival, and use novel methods to examine immunosuppresion doses and complication rates. The central hypothesis tested in this analysis is that HLA-matched recipients receive lower doses of immunosuppression and have fewer posttransplant complications. We break from tradition by examining HLA matching in both living and deceased donor kidney transplants. As secondary aims, we compare the relative impact of class I and II mismatches and describe outcomes achieved with older donors. Medicare claims linked to the United States Renal Data System database for 23,443 kidney transplants were included in the study. A total of 15,793 transplants were DR mismatched (DRMM), 5,340 manifested no DR mismatches (NODRMM), and 2,310 manifested no ABDR mismatches (NOABDRMM). Patients with NOABDRMM experienced lower adjusted risk of rejection (0.66, 95% confidence interval 0.59-0.74, P < 0.001) and lower hazard of graft loss (0.69, 0.61-0.77, P < 0.001) and death (0.76, 0.63-0.92, P < 0.001) compared with those with DRMM. The hazard of cardiac and diabetic complications was similar between recipients of NOADRMM and DRMM transplants, but the hazard of diarrhea was significantly lower (0.82, 0.73-0.92, P < 0.001) in patients with NOABDRMM. The 6-month dose of mycophenolate mofetil was lower in patients with NOABDRMM. This study validates previous studies that indicated significantly lower risks of rejection, graft loss, and death among patients with 0 HLA-A,B,DR mismatches. Use of administrative claims revealed similar rates of cardiovascular complications. However, HLA-matched deceased donor recipients received lower dosages of mycophenolate mofetil and manifested a lower risk of developing posttransplant diarrhea.

Duffy and Kidd blood group antigens: minor histocompatibility antigens involved in renal allograft rejection?

BACKGROUND

Minor histocompatibility antigens have been poorly defined. Whether Duffy (FY) and Kidd (JK), polymorphic and immunogenic blood group antigens, widely distributed in human organs, expressed and functional in the kidney, could function as minor histocompatibility antigens and be implicated in renal allograft rejection was questioned.

STUDY DESIGN AND METHODS

A retrospective, homogeneous, single-center cohort of 370 renal transplants was analyzed. In all donor/recipient pairs, FY and JK polymorphisms were identified by real-time polymerase chain reaction. In all donor/recipient pairs the matching (m) or mismatching (mm) status was defined for both systems. All biopsies were reviewed, and historical screening results for FY and JK alloantibodies and graft survival were retrospectively analyzed.

RESULTS

Although graft survival was not different between the groups, it was observed that FY mm grafts had significantly more chronic lesions compared to FY m grafts. HLA-DR11 was more frequent in both recipients (p = 0.0081) and donors (p = 0.0104) of FY mm couples without chronic allograft nephropathy, suggesting a protective effect for this molecule. JK mm grafts had more interstitial inflammation than JK m grafts (p = 0.0369).

CONCLUSION

This renal model unmasks for the first time the role of FY and-to a lesser extent-JK antigens as minor histocompatibility antigens and suggests their potential role for other clinical transplant settings.

Intravenous immunoglobulin, HLA allele typing and HLAMatchmaker facilitate successful transplantation in highly sensitized pediatric renal allograft recipients

The use of intravenous immunoglobulin (IVIG) in sensitized transplant candidates has resulted in reduced HLA antibody levels and shorter transplant wait times. In addition, the HLAMatchmaker program has been used to identify acceptable mismatches to permit transplantation in highly sensitized patients. We used IVIG desensitization in conjunction with high resolution HLA allele typing and HLAMatchmaker grading of donor offers to facilitate successful transplantation in two highly sensitized children who were awaiting second renal transplants. Both patients lost their initial transplant in <10 days to accelerated acute rejection, and were on dialysis for an average of 50 months with high panel reactive antibody (PRA) levels. They were started on monthly IVIG infusions (2 g/kg/dose). Within one wk following their third and fifth IVIG doses, both patients received a crossmatch compatible, deceased donor renal transplant selected by HLAMatchmaker as a suitable donor offer. Both patients remain rejection free with excellent renal function 19 and 15 months post-transplant, respectively. In conclusion, combining IVIG therapy and donor selection by HLA humoral epitope matching permitted successful transplantation of two highly sensitized children. Further studies in larger numbers of patients with longer follow-up are needed to determine the individual role played by, and relative importance of each component of this combined strategy.

Clinical relevance of anti-HLA antibodies detected by flow-cytometry bead-based assays--single-center experience

The purpose of this study was to define the incidence, dynamics, and profiles of anti-human leukocyte antigen antibodies (HLA-Abs) produced after kidney transplantation and their impact on graft outcome. A total of 72 first cadaver donor kidney recipients were prospectively monitored for the development of HLA-Abs using bead-based flow-cytometry assays (One Lambda FlowPRA tests). Sixteen recipients (22.2%) developed HLA-Abs after transplantation (class I, n = 7; class I+II, n = 6; class II, n = 3), in most cases (81.25%) within the first 2 weeks posttransplantation. A strong association between alloantibody presence and delayed graft function (Chi-square = 7.659, p < 0.01), acute rejection (Chi-square = 14.504, p < 0.001), chronic rejection (Chi-square = 12.84, p < 0.001), and graft loss (Chi-square = 20.283, p < 0.001) was found. Patients with higher alloantibody titers experienced acute rejections and even early graft loss, compared with those with lower titers for whom chronic rejections were more common. Immunologic complications occurred in recipients with both donor-specific and cross-reacting groups or non-donor-specific antibodies alone. A positive correlation (Pearson correlation, 0.245; p < 0.05) between HLA class I amino acid triplet incompatibility and alloantibody production was observed, mainly resulting from immunogenic triplotypes. Given the results obtained in this study, an alloantibody testing algorithm has been designed and implemented for routine monitoring and to define optimally the alloantibody reactivity in kidney transplant recipients.

Mechanisms of chronic allograft dysfunction

This review was designed to highlight new findings that have contributed to our knowledge of the pathogenesis of late graft dysfunction. Both immune and nonimmune causes contribute to its development. Specific contributors to late graft dysfunction have been recently recognized and are potential targets for new treatment options. The variables associated with late graft failure include donor age and tissue quality, brain death and other issues specific to the deceased donor, tissue injury secondary to organ preservation, alloimmune-mediated injury, and posttransplantation factors in the recipient, such as viral infections, hypertension, drug toxicity, and hyperlipidemia. One of the critical variables that is controllable is the total ischemic time; the longer the ischemic episode, the worse the long-term results of the transplant are. Another significant obstacle to long-term allograft survival is the MHC barrier. The roles of B cells and alloantibody as effectors of alloimmunity have been underestimated; emerging studies strongly suggest that previous sensitization and/or de novo donor-anti-human lymphocyte antigen (HLA) antibodies secondary to poor HLA matching portend a poor prognosis for allograft survival, even in the presence of chronic T-cell-specific immunosuppression.

Differential Immunogenicity of HLA Class I Alloantigens for the Humoral versus the Cellular Immune Response: “Towards Tailor-Made HLA Mismatching”

The immunogenicity of an individual human leukocyte antigen (HLA) class I mismatch is different for the cellular and the humoral alloimmune responses. The consequence is that the same antigen can induce a strong antibody response and no cytotoxic T lymphocyte reactivity, but the reverse can occur also. Exact knowledge of the immunogenicity of an HLA mismatch for an individual patient can lead to a strategy of tailor-made HLA mismatching if no HLA identical donor is available. Depending on the clinical situation, one should select a donor with HLA mismatches according to the humoral or cellular mismatch algorithm.

The effect of HLA class I (A and B) and class II (DR) compatibility on liver transplantation outcomes: an analysis of the OPTN database

The purpose of this study was to explore the relationship between human leukocyte antigen (HLA) compatibility and liver transplantation outcomes by analyzing the effect of HLA compatibility on 5-year graft survival. We analyzed first liver transplants between 1987 and 2002 in the Organ Procurement and Transplantation Network (OPTN) database, where A, B, or DR loci data were available. Graft failure was defined as retransplantation or death from transplant-related cause. We evaluated associations between total and locus-specific match levels and 5-year graft survival. Multivariable Cox proportional-hazard models were used to evaluate statistical interactions and adjust for the effect of potential confounders. Among 29,675 first-time transplants, the overall degree of HLA match had no effect on 5-year graft survival, even after controlling for potential confounders. Univariate and multivariable analyses showed that the 0 HLA antigen mismatch cohort of patients had higher 5-year graft failure rates than the other 6 antigen mismatch groups. However, this occurred in a small group with a disproportionately large number of live donors and split-liver recipients. When these recipients were excluded from the analysis, the effect was no longer seen. Finally, multivariable, locus-specific analyses showed no association between 5-year graft survival and degree of match/mismatch and the A, B, or DR loci. In conclusion, this careful examination of the OPTN database, with respect to HLA match or mismatch and liver graft survival, reaffirms that HLA matching has no clinically significant impact on this outcome.