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Eurotransplant is responsible for the international allocation of organs between eight countries in Europe. All HLA laboratories affiliated to Eurotransplant must be EFI or ASHI-accredited and must participate in the Eurotransplant external proficiency testing (EPT) program, organized by the Eurotransplant Reference Laboratory (ETRL). EPT within Eurotransplant has a long tradition, starting in 1978. The current EPT program consists of the following schemes: HLA typing including serology, CDC crossmatching, HLA-specific antibody detection, and identification. Participants enter the results of laboratory tests using a webbased application. Assessed results are visible on the website. An additional component called "patient-based cases" runs since 2016. Results are summarized and published on the EPT website. Furthermore, these results are discussed during the annual extramural tissue typers meeting, which is organized by the ETRL. Thanks to this EPT program, the performance of all HLA laboratories affiliated to Eurotransplant can be monitored and corrected, if necessary. Because all affiliated laboratories are assessed in the same EPT program, where these laboratories show to be consistent in most of their results, Eurotransplant EPT has proven to be an efficient tool to create a more uniform level of quality of histocompatibility testing within Eurotransplant. [ABSTRACT FROM AUTHOR]

Vascularized composite allotransplantation (VCA) is the transplantation of multiple tissue types as a solution for devastating injuries. Despite the highly encouraging functional outcomes of VCA, the consequences of long-term immunosuppression remain the main obstacle in its application. In this review, we provide researchers and surgeons with a summary of the latest advances in the field of cell-based therapies for VCA tolerance. Four electronic databases were searched: PubMed, Scopus, Cumulative Index to Nursing and Allied Health Literature , and Web of Science. We used the Preferred Reporting Items for Systematic Reviews and Meta-Analysis as the basis of our organization. Hematopoietic stem cells prolonged VCA survival. A combination of immature dendritic cells and tacrolimus was superior to tacrolimus alone. T cell Ig domain and mucin domain modified mature dendritic cells increased VCA tolerance. Bone marrow-derived mesenchymal stem cells prolonged survival of VCAs. A combination of adipose-derived mesenchymal stem cells, cytotoxic T-lymphocyte antigen 4 immunoglobulin, and antilymphocyte serum significantly improved VCA tolerance. Ex-vivo allotransplant perfusion with recipient's bone marrow-derived mesenchymal stem cells increased VCA survival. Recipient's adipose-derived mesenchymal stem cells and systemic immunosuppression prolonged VCA survival more than any of those agents alone. Additionally, a combination of peripheral blood mononuclear cells shortly incubated in mitomycin and cyclosporine significantly improved VCA survival. Finally, a combination of donor recipient chimeric cells, anti-αβ-T cell receptor (TCR), and cyclosporine significantly prolonged VCA tolerance. Evidence from animal studies shows that cell-based therapies can prolong survival of VCAs. However, there remain many obstacles for these therapies, and they require rigorous clinical research given the rarity of the subjects and the complexity of the therapies. The major limitations of cell-based therapies include the need for conditioning with immunosuppressive drugs and radiation, causing significant toxicity. Safety concerns also persist as most research is on animal models. While completely replacing traditional immunosuppression with cell-based methods is unlikely soon, these therapies could reduce the need for high doses of immunosuppressants and improve VCA tolerance. [ABSTRACT FROM AUTHOR]

The virtual crossmatch (VXM) has become a critical tool to predict the compatibility between an organ donor and a potential recipient. Yet, nonstandardized laboratory practice can lead to variability in VXM interpretation. Therefore, UCLAs VXM Exchange survey was designed to understand factors that influence the variability of VXM prediction in the presence of HLA donor-specific antibody (DSA). Thirty-six donor blood samples and 72 HLA reference sera were sent to 35 participating laboratories to perform HLA antibody testing, flow crossmatch (FXM), and VXM from 2014 to 2019, consisting of 144 T/B-cell FXM pairs and 112 T/B-cell VXM pairs. In the FXM survey, 86% T-cell FXM and 84% B-cell FXM achieved >80% concordance among laboratories. In the VXM survey, 81% T-cell VXM and 80% VXM achieved >80% concordance. The concordance between FXM and VXM was 79% for T cell and 87% for B cell. The consensus between VXM and FXM was high with strong DSA. However, significant variability was observed in sera with (1) very high titer antibodies that exit prozone effect; (2) weak-to-moderate DSA, particularly in the presence of multiple weak DSAs; and (3) DSA against lowly expressed antigens. With the increasing use the VXM, standardization and continuous learning via exchange surveys will provide better understanding and quality controls for VXM to improve accuracy across all centers.

Background: Pronase pretreatment can reduce rituximab (RTX) interference by degrading CD20 in B-cell flow cytometry crossmatch (FCXM) testing. However, it may also reduce the assay sensitivity by degrading HLA molecules. We investigated the effects of various pronase concentrations on RTX interference and the analytical sensitivity of B-cell FCXM testing. Methods: Using 59 patient serum samples and 38 donor lymphocyte samples, we designed 97 recipient–donor pairs and divided them into three groups according to RTX use and the presence of weak-to-moderate donor HLA-specific antibody (DSA) reactions: RTX+/DSA−, RTX+/DSA+, and RTX−/DSA+. FCXM was performed after pretreating lymphocytes with six different pronase concentrations (0, 0.5, 1, 2, 3, and 4 mg/mL). Results: With B-FCXM testing, false-positive results due to RTX in the RTX+/DSA– group markedly decreased with increasing pronase concentrations. The median channel shift values in the RTX+/DSA+ and RTX−/DSA+ groups did not significantly decrease when the pronase concentration was increased from 1 mg/mL to 2 or 3 mg/mL. All eight RTX+/DSA+ cases that were positive at 1 mg/mL pronase but negative at 2 or 3 mg/mL had mean fluorescence intensity (MFI) DSA values of less than 3,000 except for DQ5 (MFI: 5,226). With T-cell FCXM, false-positive results were observed in 2.9% of 315 FCXM tests with pronase pretreatment. Conclusions: Higher concentrations (2 or 3 mg/mL) of pronase effectively eliminated RTX interference but still carried a risk for false negativity for weak DSA reactions in B-cell FCXM. Higher pronase concentrations can be used as an auxiliary method to detect moderate-to-strong DSA reactions in RTX-treated patients. [ABSTRACT FROM AUTHOR]

Histocompatibility testing is pivotal in any renal transplantation workup, aimed at enhancing prospective donor recipient compatibility and improving transplant outcomes. The evolution and advancement of histocompatibility testing, particularly HLA typing, have significantly improved its precision. This study outlines the historical progression from serologic to DNA-based HLA typing, emphasizing the role of HLA proteins in immune response. Anti-HLA antibodies, targeting HLA proteins, pose challenges in renal transplantation. Monitoring and managing these antibodies are critical for renal transplant success. Complement-dependent cytotoxicity crossmatch and flow cytometry crossmatch are essential techniques for assessing donor–recipient compatibility. Panel-reactive antibody assesses antibodies against a panel of donor antigens, often HLA. Higher PRA levels (percentage) complicate donor matching, requiring specialized protocols. Virtual crossmatch evaluates recipient anti-HLA antibodies against potential donors through synthetic beads. This approach predicts crossmatch outcomes by comparing antibody profiles, offering a valuable tool for the risk assessment of renal transplantation. Despite advancements, a comprehensive understanding of alloreactive immune responses requires a combination of assays, emphasizing the importance of a multifaceted approach in histocompatibility testing. This is an attempt to compile the relevant information, providing a basis for comparison in a clear and foundational format for histocompatibility testing laboratories.

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. [ABSTRACT FROM AUTHOR]

Histocompatibility testing is pivotal in any renal transplantation workup, aimed at enhancing prospective donor recipient compatibility and improving transplant outcomes. The evolution and advancement of histocompatibility testing, particularly HLA typing, have significantly improved its precision. This study outlines the historical progression from serologic to DNA-based HLA typing, emphasizing the role of HLA proteins in immune response. Anti-HLA antibodies, targeting HLA proteins, pose challenges in renal transplantation. Monitoring and managing these antibodies are critical for renal transplant success. Complement-dependent cytotoxicity crossmatch and flow cytometry crossmatch are essential techniques for assessing donor–recipient compatibility. Panel-reactive antibody assesses antibodies against a panel of donor antigens, often HLA. Higher PRA levels (percentage) complicate donor matching, requiring specialized protocols. Virtual crossmatch evaluates recipient anti-HLA antibodies against potential donors through synthetic beads. This approach predicts crossmatch outcomes by comparing antibody profiles, offering a valuable tool for the risk assessment of renal transplantation. Despite advancements, a comprehensive understanding of alloreactive immune responses requires a combination of assays, emphasizing the importance of a multifaceted approach in histocompatibility testing. This is an attempt to compile the relevant information, providing a basis for comparison in a clear and foundational format for histocompatibility testing laboratories. [ABSTRACT FROM AUTHOR]

Simple Summary: This study examines the viability of liver grafts from donors aged 85 years and older in liver transplantation (LT) compared to those from younger donors under 40 years old. The research, conducted on data from 2005 to 2023, evaluates post-LT outcomes using propensity score matching. Despite lower 5-year survival rates in the elderly group before matching, the proposed nomogram provides a more acceptable 10-year post-LT survival using grafts from older donors. Notably, the study emphasizes the importance of proper matching, particularly for recipients with hepatocellular carcinoma (HCC), in achieving satisfactory long-term results amid organ scarcity. Background: Despite the ongoing trend of increasing donor ages in liver transplantation (LT) setting, a notable gap persists in the availability of comprehensive guidelines for the utilization of organs from elderly donors. This study aimed to evaluate the viability of livers grafts from donors aged ≥85 years and report the post-LT outcomes compared with those from "ideal" donors under 40 years old. Methods: Conducted retrospectively at a single center from 2005 to 2023, this study compared outcomes of LTs from donors aged ≥85 y/o and ≤40 y/o, with the propensity score matching to the recipient's gender, age, BMI, MELD score, redo-LT, LT indication, and cause of donor death. Results: A total of 76 patients received grafts from donors ≥85 y/o and were compared to 349 liver grafts from donors ≤40 y/o. Prior to PSM, the 5-year overall survival was 63% for the elderly group and 77% for the young group (p = 0.002). After PSM, the 5-year overall survival was 63% and 73% (p = 0.1). A nomogram, developed at the time of graft acceptance and including HCC features, predicted 10-year survival after LT using a graft from a donor aged ≥85. Conclusions: In the context of organ scarcity, elderly donors emerge as a partial solution. Nonetheless, without proper selection, LT using very elderly donors yields inferior long-term outcomes compared to transplantation from very young donors ≤40 y/o. The resulting nomogram based on pre-transplant criteria allows for the optimization of elderly donor/recipient matching to achieve satisfactory long-term results, in addition to traditional matching methods. [ABSTRACT FROM AUTHOR]

Background: For many years, transplantation outcomes were uncertain and not hopeful, until histocompatibility testing spread. Common criteria for histocompatibility assays and communications' improvement allowed an efficient organ sharing system. The possibility of organ exchanges is closely linked to the importance of interlaboratory comparisons for histocompatibility and immunogenetics methods. The external proficiency testing (EPT) systems are the most powerful quality assurance tools. They help achieve harmonization of analyses, set a standard of performance, and a common interpretation. Methods: The external quality assurance program for diagnostic immunology laboratories (Garantía Externa de Calidad para Laboratorios de Inmunología Diagnóstica, GECLID) program nowadays runs 13 external quality assurance (EQA) histocompatibility and immunogenetics schemes, with the first of them from 2011 to date: serological and molecular: low- and high-resolution human leukocyte antigen (HLA), human platelet antigen (HPA), and killer inhibitory receptor (KIR) typing(HLA-B*27, HLA-B*57:01, and coeliac disease-related HLA), cell-dependent cytotoxicity (CDC) and flow cytometry (FC) crossmatches, anti-HLA and anti-HPA antibodies, and chimerism. Results: A total of 85 laboratories participated in this subprogram in the last 12years reporting over 1.69 M results: 1.46 M for anti-HLA and anti-HPA antibodies, 203.810 molecular typing data (HLA, HPA, and KIR genes), 2.372 for chimerism analyses, and 39.352 for crossmatches. Based on the European Federation for Immunogenetics (EFI) standards for EPT providers, the mean success rates ranged from 99.2% for molecular typing schemes and antibodies and 94.8% for chimerism, was 96.7% regarding crossmatches, and was 98.9% in serological typing. In 2022, 61.3% of the participating laboratories successfully passed every HLA EQA scheme, although 87.9% annual reports were satisfactory. Most penalties were due to nomenclature errors or misreporting of the risk associated to HLA and disease. Conclusion: This EQA confirms the reliability of HLA and immunogenetics assays in routine care. There is little heterogeneity of results of different assays used by participating laboratories, even when in-house assays are used. Reliability of test results is reasonably granted. [ABSTRACT FROM AUTHOR]

The introduction of Next‐Generation Sequencing (NGS) methodology in the histocompatibility testing for both allo‐HSCT and solid organ transplantation enables the sequencing of all HLA genes, which in turn leads to the discovery of many new HLA alleles. Over the last 3 years, we have identified 28 novel alleles (HLA‐A*02:1079, A*03:01:01:112, A*11:01:01:83, A*11:01:01:87, A*24:595, A*68:01:01:15, B*07:02:01:107, B*08:01:01:67, B*08:01:01:69, B*13:02:01:25, B*15:01:82, B*15:18:08, B*18:01:01:76, B*27:02:06, B*27:05:02:34, B*40:06:01:17, B*40:517, C*04:01:01:173, C*04:477, C*05:276, C*07:01:01:130, C*12:03:80, C*12:03:01:62, DQA1*05:01:01:10, DPB1*13:01:07, DPB1*1146:01, DPB1*1456:01 and DPB1*1514:01) using the NGS method. The presented data emphasises the benefits gained by the utilisation of the NGS‐based techniques in HLA genotyping but also provides new insight on the HLA polymorphism in the Croatian population. [ABSTRACT FROM AUTHOR]

Eurotransplant is responsible for the international allocation of organs between eight countries in Europe. All HLA laboratories affiliated to Eurotransplant must be EFI or ASHI-accredited and must participate in the Eurotransplant external proficiency testing (EPT) program, organized by the Eurotransplant Reference Laboratory (ETRL). EPT within Eurotransplant has a long tradition, starting in 1978. The current EPT program consists of the following schemes: HLA typing including serology, CDC crossmatching, HLA-specific antibody detection, and identification. Participants enter the results of laboratory tests using a web-based application. Assessed results are visible on the website. An additional component called “patient-based cases” runs since 2016. Results are summarized and published on the EPT website. Furthermore, these results are discussed during the annual extramural tissue typers meeting, which is organized by the ETRL. Thanks to this EPT program, the performance of all HLA laboratories affiliated to Eurotransplant can be monitored and corrected, if necessary. Because all affiliated laboratories are assessed in the same EPT program, where these laboratories show to be consistent in most of their results, Eurotransplant EPT has proven to be an efficient tool to create a more uniform level of quality of histocompatibility testing within Eurotransplant.

Various computational approaches have been developed to annotate epigenomes on a per-position basis by modeling combinatorial and spatial patterns within epigenomic data. However, such annotations are less suitable for gene-based analyses. We present ChromGene, a method based on a mixture of learned hidden Markov models, to annotate genes based on multiple epigenomic maps across the gene body and flanks. We provide ChromGene assignments for over 100 cell and tissue types. We characterize the mixture components in terms of gene expression, constraint, and other gene annotations. The ChromGene method and annotations will provide a useful resource for gene-based epigenomic analyses.

The Histocompatibility and Immunogenetics laboratories provide disease association and pharmacogenetic analyses as well as the tests required for transplantation immunology and transfusion medicine. They perform Human Leukocyte Antigen (HLA) genotyping in patients/recipients and potential donor candidates for solid organ and stem cell transplants using various molecular methods, and determine mismatches. In addition, they also perform HLA antibody tests to detect anti-HLA antibodies in patients and flow crossmatches to evaluate donor-recipient compatibility. Evidence-based clinical guidelines have emphasized the importance of laboratory tests in clinical practices for a long time. Understanding the principles of Quality Control and External Quality Assurance is a fundamental requirement for the effective management of Tissue Typing laboratories. When these processes are effectively implemented, errors in routine assays for transplantation are reduced and quality is improved. In this review, the importance of Quality Assurance, Quality control and proficiency testing in Histocompatibility and Immunogenetic testing, the necessity of external proficiency testing (EPT) for accreditation, and existing and potential EPT programmes will be reviewed and evaluated in the light of the literature. [ABSTRACT FROM AUTHOR]

Allogeneic transplantation is a multi-step process involving many clinicians and laboratory personnel working together to achieve a common goal--to maximize the recipients' chance of survival and to improve their quality of life. One of the key elements of the process is to ensure high quality, accuracy, and reliability of histocompatibility testing. This manuscript presents: the development and organizational principles of the national system of supervision and control of histocompatibility laboratories in Poland, problems faced by these laboratories, availabe proficiency testing schemes, as well as suggestions and prospects for the future raised by members of the Polish histocompatibility community. [ABSTRACT FROM AUTHOR]

Cytomegalovirus (CMV) is an enveloped double-stranded DNA virus, that in the healthy population, causes a mild flu-like illness. CMV is the most common, opportunistic viral pathogen in the solid organ transplant (SOT) setting and is associated with considerable morbidity, mortality, and graft loss. CMV causes lifelong infection, and organs from seropositive donors may transmit infection, potentially causing severe disease in a seronegative patient undergoing solid organ transplantation. Donor and recipient CMV IgG serological screening is utilised to stratify the risk of post-transplant CMV infection. The serostatus of both the donor and the recipients are key predictors of the risk of CMV after transplant and guide decisions on antiviral prophylaxis or pre-emptive treatment strategies. In SOT recipients, CMV can occur as a primary infection, donor-derived infection, or because of reactivation of latent virus in the setting of immunosuppression. Anti-viral prophylaxis and pre-emptive therapy are the main approaches for prevention of CMV in the SOT population. Valganciclovir and intravenous Ganciclovir remain drugs of choice for CMV management in all consensus guidelines. Currently, there is no prophylactic vaccine available. [ABSTRACT FROM AUTHOR]

Introduction: The large HLA diversity in worldwide populations is a major challenge for matched unrelated haematopoietic stem cell (HSC) donor searches. The impact of regional diversity on the effective HSC donor selection has not been documented so far for national registries. Methods: The aim of the study was to analyse the 532 consecutive work-up (WU) requests received by Swiss Blood Stem Cells (SBSC), over a 9-year period (2011–2019) with respect to criteria including the geographical origin of the donors as derived from the postal codes, countries requesting SBSC donors, HLA-matching parameters, and patients' HLA haplotype frequencies. Results: Highly matched donors (10/10) represented 73.5% of the WU, whereas 8–9/10 mismatched donors accounted for 24.0%. The remaining donors were 7–8/8 matched (1.7%) or had an unknown matching grade (0.8%). Among the 10/10 matched patient/donor pairs with full HLA-DPB1 typing information, the rate of 11–12/12 matched donors was 73.3%. Of the 532 WU requests, 47.6% were for patients of the four neighbouring countries and for national patients. The ratio of WU requests was directly proportional to the total number of donors registered in each region (Pearson's r = 0.977). However, for two regions (lemanic and north-eastern areas of Switzerland (CH)), the proportion of selected donors was slightly above the min-max ratio of registered donors throughout the study period. The number of WU requests differed between countries when considering donors from the northern and southern parts of the country delineated by the alpine barrier. Conclusion: This study shows the value of the SBSC registry for both national and international patients. Two countries (USA and Germany) which operate the two worldwide largest registries (>19 million donors) requested 30% of SBSC registered donors, while the Swiss transplant centres accounted for 13% of the WU requests. When considering the geographic origin of SBSC donors, we observe a correlation of WU requests with the total number of registered donors in each subregion. This finding thus supports recruitment efforts throughout all regions. Interestingly, donors from three regions (lemanic area, Zurich and Ticino) are slightly over-represented, which is possibly related to higher HLA haplotypic diversity. A focus on planning recruitment in these regions might contribute to more successful donor searches. [ABSTRACT FROM AUTHOR]

Next generation sequencing (NGS) is being applied for HLA typing in research and clinical settings. NGS HLA typing has made it feasible to sequence exons, introns and untranslated regions simultaneously, with significantly reduced labor and reagent cost per sample, rapid turnaround time, and improved HLA genotype accuracy. NGS technologies bring challenges for cost-effective computation, data processing and exchange of NGS-based HLA data. To address these challenges, guidelines and specifications such as Genotype List (GL) String, Minimum Information for Reporting Immunogenomic NGS Genotyping (MIRING), and Histoimmunogenetics Markup Language (HML) were proposed to streamline and standardize reporting of HLA genotypes. As part of the 17th International HLA and Immunogenetics Workshop (IHIW), we implemented standards and systems for HLA genotype reporting that included GL String, MIRING and HML, and found that misunderstanding or misinterpretations of these standards led to inconsistencies in the reporting of NGS HLA genotyping results. This may be due in part to a historical lack of centralized data reporting standards in the histocompatibility and immunogenetics community. We have worked with software and database developers, clinicians and scientists to address these issues in a collaborative fashion as part of the Data Standard Hackathons (DaSH) for NGS. Here we report several categories of challenges to the consistent exchange of NGS HLA genotyping data we have observed. We hope to address these challenges in future DaSH for NGS efforts.

HLA‐DQA1*05:05:17:03 differs from HLA‐DQA1*05:05:01:02 by a single base substitution in exon 1 and HLA‐DQA1*05:05:17:01 within introns 1 and 2. [ABSTRACT FROM AUTHOR]

HLA‐C*06:372 differs from HLA‐C*06:02:01:01 by a single substitution in exon 4. [ABSTRACT FROM AUTHOR]

HLA antibodies are typically produced after exposure to transplanted tissue, pregnancy, and blood products. Sensitization delays access to transplantation and preclude utilization of donor organs. Infections and vaccinations have also been reported to result in HLA antibody formation. It is not known if patients develop HLA antibodies after infection with SARS-CoV-2. Here we analyzed a series of eighteen patients waiting for kidney transplantation who had symptomatic COVID-19 disease and recovered. None of the patients in this initial series developed de novo HLA antibodies. Notably, there was no increase in preexisting HLA antibodies in four highly sensitized patients with a CPRA > 80%. These preliminary data suggest that there may not be a need to repeat HLA antibody testing or perform a physical crossmatch on admission serum before kidney transplant for COVID-19 recovered patients. Data from a large number of patients with different demographics needed.

Molecular matching is a new approach for virtual histocompatibility testing in organ transplantation. The aim of our study was to analyze whether the risk for de novo donor‐specific HLA antibodies (dnDSA) after lung transplantation (LTX) can be predicted by molecular matching algorithms (MMA) and their combination. In this retrospective study we included 183 patients undergoing LTX at our center from 2012–2020. We monitored dnDSA development for 1 year. Eplet mismatches (epMM) using HLAMatchmaker were calculated and highly immunogenic eplets based on their ElliPro scores were identified. PIRCHE‐II scores were calculated using PIRCHE‐II algorithm (5‐ and 11‐loci). We compared epMM and PIRCHE‐II scores between patients with and without dnDSA using t‐test and used ROC‐curves to determine optimal cut‐off values to categorize patients into four groups. We used logistic regression with AIC to compare the predictive value of PIRCHE‐II, epMM, and their combination. In total 28.4% of patients developed dnDSA (n = 52), 12.5% class I dnDSA (n = 23), 24.6% class II dnDSA (n = 45), and 8.7% both class II and II dnDSA (n = 16). Mean epMMs (p‐value = 0.005), mean highly immunogenic epMMs (p‐value = 0.003), and PIRCHE‐II (11‐loci) (p = 0.01) were higher in patients with compared to without class II dnDSA. Patients with highly immunogenic epMMs above 30.5 and PIRCHE‐II 11‐loci above 560.0 were more likely to develop dnDSA (31.1% vs. 14.8%, p‐value = 0.03). The logistic regression model including the grouping variable showed the best predictive value. MMA can support clinicians to identify patients at higher or lower risk for developing class II dnDSA and might be helpful tools for immunological risk assessment in LTX patients. [ABSTRACT FROM AUTHOR]

Simple Summary: Egypt has the highest prevalence of hepatitis C infection in the world with a dramatic increase in the incidence of hepatocellular carcinoma (HCC) observed during the last decade. Currently, HCC is the most prevalent cancer in men and the second most prevalent cancer in women in Egypt. There are limited published data on the implication of host KIR genotypes and the progression of chronic hepatitis C virus (HCV) infection to HCC. We describe the first analysis of Egyptian KIR genotypes from the Nile Delta region. The findings of this study suggest that KIR haplotype AA, that contains dominantly inhibitory genes, was less frequent in HCC patients compared to chronic HCV patients and healthy control subjects. Therefore, haplotype AA may have a crucial role in host defense against HCC progression. In Egypt, hepatocellular carcinoma (HCC) is the most prevalent cancer in men and the second most prevalent cancer in women. In addition, Egypt has one of the highest prevalences of hepatitis C infection in the world. The aim of the present work was to study the potential role of the 16 KIR genes in the outcome of individuals with chronic hepatitis C virus (HCV) infection in Egypt. The study was carried out under an IRB-approved protocol. Sequence-Specific-Primer-PCR (SSP-PCR) was used for KIR genotyping of germline DNA extracted from peripheral blood leukocytes or from the non-tumor liver of 83 HCC patients, 100 patients with chronic HCV infection without HCC, and 120 matched healthy controls. Out of the 83 HCC patients, only 7 (8.4%) were treated by interferon and/or interferon Ribavirin combination, while for the remaining patients 50 (60.2%) received no prior HCV therapy and 26 (31.3%) were treated with direct-acting antiviral (DAA). Our results showed that KIR haplotype AA that contains more inhibitory KIR genes and fewer activating genes was observed with a significantly lower frequency in HCC patients (6/83, 7.2%) compared to chronic HCV (27/100, 27.0%) (p = 0.0005, OR = 0.21 [0.08–0.53]) and healthy controls (29/119, 24.4%) (p = 0.001, OR = 0.24 [0.09–0.61]). In addition, the frequency of genotype 6 (G6) which contains all the KIR genes was significantly high in the HCC patients (16/83, 19.3%) compared to chronic HCV (8/100, 8.0%) (p = 0.02, OR = 2.7 [1.11–6.79]) and healthy controls (8/119, 6.7%) (p = 0.006, OR = 3.31 [1.35–8.16]). Activating KIR genes 2DS1 and 3DS1 were significantly higher in HCC patients (48/83, 57.83% and 45/83, 54.22%) compared to the chronic HCV patients (36/100, 36% and 34/100, 34%), p = 0.028, 0.027, respectively. Our results are contrary to a prior work on HCC from patients with HCV who were mostly treated by interferon-based therapies. In conclusion, KIR haplotype AA has an important role in host defense against HCC progression especially in patients treated by DAA, suggesting an important role of the KIR genotype status on the outcome of chronic HCV infection. [ABSTRACT FROM AUTHOR]

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PurposeUltrahigh resolution (UHR) HLA matching is reported to result in better outcomes following unrelated donor hematopoietic cell transplantation, improving survival and reducing post-transplant complications. However, most studies included relatively small numbers of patients. Here we report the findings from a large, multicenter validation study.MethodsUHR HLA typing was available on 5,140 conventionally 10 out of 10 HLA-matched patients with malignant disease transplanted between 2008 and 2017.ResultsAfter UHR HLA typing, 82% of pairs remained 10 out of 10 UHR-matched; 12.3% of patients were 12 out of 12 UHR HLA-matched. Compared with 12 out of 12 UHR-matched patients, probabilities of grade 2-4 acute graft-versus-host disease (aGVHD) were significantly increased with UHR mismatches (overall P = .0019) and in those patients who were HLA-DPB1 T-cell epitope permissively mismatched or nonpermissively mismatched (overall P = .0011). In the T-cell-depleted subset, the degree of UHR HLA mismatch was only associated with increased transplant-related mortality (TRM) (overall P = .0068). In the T-cell-replete subset, UHR HLA matching was associated with a lower probability of aGVHD (overall P = .0020); 12 out of 12 UHR matching was associated with reduced TRM risk when compared with HLA-DPB1 T-cell epitope permissively mismatched patients, whereas nonpermissive mismatching resulted in a greater risk (overall P = .0003).ConclusionThis study did not confirm that UHR 12 out of 12 HLA matching increases the probability of overall survival but does demonstrate that aGVHD risk, and in certain settings TRM, is lowest in UHR HLA-matched pairs and thus warrants consideration when multiple 10 out of 10 HLA-matched donors of equivalent age are available.

The International human leukocyte antigen (HLA) and Immunogenetics Workshops (IHIWs) have fostered international collaborations of researchers and experts in the fields of HLA, histocompatibility and immunology. These IHIW collaborations have comprised many projects focused on achieving a variety of specific goals. The international and collaborative nature of these projects necessitates the collection and analysis of complex data generated in multiple laboratories, often using multiple methods of acquisition. Collection and storage of these data in a consistent way adds value to IHIW projects, which can be extended to future work. DNA-based genotyping data, especially HLA genotyping data, can be transmitted in the form of a Histoimmunogenetics Markup Language (HML) document. HML facilitates clear communication of a genotype and supporting metadata, such as, sequencing platform, laboratory assays, consensus sequence, and interpretation. Sequence information can be reported relative to known reference sequences, which add meaning and context to genotypes. Selecting the correct reference sequence for a given allele sequence is nuanced, and guidelines have emerged through collaborative community efforts such as Data Standards Hackathons. Here, we describe the guidelines established for the selection of reference sequences to be used in transmission of HLA (and MICA/MICB) genotyping data for the 18th IHIW.

HLA‐B*41:84 has a single base substitution in exon 2, altering glutamic acid to glutamine'. [ABSTRACT FROM AUTHOR]

Anti-human leukocyte antigen (HLA) donor-specific antibodies (DSAs) are associated with antibody-mediated rejection and chronic allograft nephropathy in kidney transplantation. The interpretation of immunological assays for DSAs can be challenging due to discordant results. In this report, we present two cases of kidney transplantation involving patients with anti-HLA-C DSAs. We discuss the interpretation of their immunological tests, including complement-dependent cytotoxicity (CDC) crossmatches, flow cytometry crossmatches, and donor-specific antigen using single-antigen bead (SAB) assays, which influenced therapeutic decisions. In the first case, the patient exhibited isolated B-cell-positive crossmatch and autoantibodies, prompting the consideration of polyclonal autoantibodies in the context of underlying hepatitis C infection. The SAB assay detected only one DSA against HLA-C 03:03:01 (mean fluorescence intensity - 27,127). After careful evaluation and confirmation of negative CDC crossmatch, transplantation proceeded, and the patient demonstrated good graft function. In the second case, the patient showed a positive T-cell crossmatch along with anti-Class I HLA DSAs against HLA C*07:01 and HLA C*07:02. Despite these findings, transplantation was performed based on the absence of complement-binding antibodies. The patient experienced good graft recovery with stable kidney function. The presence of HLA-C DSAs poses challenges in transplantation decision-making. Despite conflicting studies, the pathological nature of these antibodies has been demonstrated. Careful interpretation of immunological tests and consideration of the overall clinical context are essential in making therapeutic decisions. Further research is needed to understand the clinical significance of HLA-C DSAs and their impact on graft outcomes. [ABSTRACT FROM AUTHOR]

The presence of preformed cytotoxic donor‑specific antibodies (DSAs) has been associated with inferior allograft outcomes in the immediate posttransplant period. Since the 1970s, the primary method for determining the presence of DSAs has been the complement‑dependent cytotoxicity crossmatch. Solid phase assays on the Luminex platform were introduced in India in 2010 in the form of human leukocyte antigen antibody screening, single antigen bead (SAB) assay and lysate‑based crossmatch (LumXM) to identify low titer antibodies, which are deleterious to allograft. Instead of SAB, LumXM has been popularly used in India to identify DSAs and also called DSA crossmatch, which is not recommended or validated in International literature for denying or accepting to transplant a patient due to its fallacies. We are reporting three cases which showcase the flawed nature of this test and the implications of this test on day to day practice in transplantation. [ABSTRACT FROM AUTHOR]

By studying the local effects of a new type of injectable cosmetic filler implanted into the animal to explore the mechanism of remodeling and cosmetic effect of this kind of product. Take 12 rabbits and select 4 implantation points on both sides of the spine, respectively, and implant the test sample (PLLA) and negative control sample (HDPE) into the subcutaneous tissues on both sides. In the same way, take another 12 rabbits and implant the marketing control sample (cross-linked sodium hyaluronate) and negative control sample (HDPE) into the subcutaneous tissues on both sides. The animals were executed at 1 week, 4 weeks, 13 weeks and 52 weeks respectively, and Hematoxylin–Eosin staining, Masson trichrome staining and immunofluorescence staining were performed to characterize the local effects in vivo and the expression of type I collagen (Col. I), type III collagen (Col.III) and matrix metalloproteinase 9 (MMP-9). Good histocompatibility of the test sample and the marketing control sample were found. The foreign body reaction of marketing control sample was more intense than that of the test sample after 13 weeks. The foreign body reaction of testing sample was more intense after 52 weeks, while that of the marketing control sample was more stable. With the process of tissue repair, the collagen fibers of test samples and marketing control samples gradually increased after implantation. Type I collagen was mainly found inside the fiber capsule, while type III collagen was mainly found outside. The positive expression of matrix metalloproteinase 9 gradually increased, the positive expression of test samples increased significantly after 52 weeks, while that of marketing control samples did not change significantly. Good histocompatibility of PLLA filler is found. Matrix metalloproteinase 9 participates in foreign body reaction and collagen formation, which can reflect the process of tissue remodeling. [ABSTRACT FROM AUTHOR]

Although hematopoietic cell transplantation from an HLA-matched unrelated donor is potentially curative for hematologic malignancies, survival is lower for African Americans compared with Caucasians. Because only approximately 20% of African Americans will have an HLA-matched unrelated donor, many of these patients undergo HLA-haploidentical relative or umbilical cord blood transplantation. In this study, we analyzed outcomes after HLA-haploidentical related donor (n = 249) and umbilical cord blood (n = 118) transplantations in African American patients with hematologic malignancy between 2008 and 2016. The predominant disease was acute myelogenous leukemia for recipients of both types of donor grafts. The incidences of grade II-IV and III-IV acute graft-versus-host disease were higher after umbilical cord blood transplantation compared with HLA-haploidentical relative transplantation (56% and 29%, respectively, versus 33% and 11%, respectively; P < .0001). The 2-year incidence of transplantation-related mortality adjusted for age and conditioning regimen intensity was higher after umbilical cord blood transplantation compared with HLA-haploidentical related donor transplantation (31% versus 18%; P = .008); however, there were no between-group differences in the 2-year adjusted incidence of relapse (30% versus 34%; P = .51), overall survival (54% versus 57%; P = .66), or disease-free survival (43% versus 47%; P = .46). Our findings show that the use of HLA-haploidentical and umbilical cord blood transplants expands the access to transplantation with comparable leukemia-free and overall survival for African Americans with hematologic malignancies.

A match of HLA loci between patients and donors is critical for successful hematopoietic stem cell transplantation. However, the extreme polymorphism of HLA loci - an outcome of millions of years of natural selection - reduces the chances that two individuals will carry identical combinations of multilocus HLA genotypes. Further, HLA variability is not homogeneously distributed throughout the world: African populations on average have greater variability than non-Africans, reducing the chances that two unrelated African individuals are HLA identical. Here, we explore how self-identification (often equated with ethnicity or race) and genetic ancestry are related to the chances of finding HLA compatible donors in a large sample from Brazil, a highly admixed country. We query REDOME, Brazils Bone Marrow Registry, and investigate how different criteria for identifying ancestry influence the chances of finding a match. We find that individuals who self-identify as Black and Mixed on average have lower chances of finding matches than those who self-identify as White (up to 57% reduction). We next show that an individuals African genetic ancestry, estimated using molecular markers and quantified as the proportion of an individuals genome that traces its ancestry to Africa, is strongly associated with reduced chances of finding a match (up to 60% reduction). Finally, we document that the strongest reduction in chances of finding a match is associated with having an MHC region of exclusively African ancestry (up to 75% reduction). We apply our findings to a specific condition, for which there is a clinical indication for transplantation: sickle-cell disease. We show that the increased African ancestry in patients with this disease leads to reduced chances of finding a match, when compared to the remainder of the sample, without the condition. Our results underscore the influence of ancestry on chances of finding compatible HLA matches, and indicate that efforts guided to increasing the African component of registries are necessary.

The UCLA Immunogenetics Center is an Immunogenetics and Histocompatibility laboratory that performs testing for multiple transplant programmes within and outside of UCLA. The single antigen bead (SAB) test is a high complexity luminex bead test used to assess pretransplant and post-transplant patients for the presence of pathogenic human leucocyte antigen donor-specific antibody associated with allograft rejection. Efficient reporting of the SAB test has been difficult as data analysis and reports are generated in the laboratory information system (LIS) and uploaded to the electronic medical record (EMR) as PDFs. To solve this, we recently developed a state of the art reporting workflow allowing discrete reporting of SAB data (antibody specificity, mean fluorescent intensity and interpretative comments) from the LIS HistoTrac to UCLA Health System's EMR EPIC:CareConnect. However, a proportion of tests did not report to the EMR appropriately. Baseline system performance data evaluated over a 10-week period showed that ~4.5/100 tests resulted in EPIC as 'preliminary result' or 'in process' instead of 'final result' with only common cause variation. Quality improvement methods were employed to improve the process with the SMART Aim of reporting 100% of tests as 'final result'. Pareto analysis identified two errors accounting for 79% of common system-level failures-status errors and interface errors. We hypothesised that addressing the status error would reduce or eliminate the interface errors. We used the Model For Improvement to test a reprogramming intervention. Status and interface errors were completely resolved through the process improvement. Continuous monitoring revealed a system-level shift with only ~1.9/100 tests resulting inappropriately. Through the audit process, the remaining common system-level failures were identified and resolved. Therefore, 100% of tests result to EPIC as 'final result'. The study demonstrates that high complexity SAB bead data can be efficiently reported EPIC:CareConnect from HistoTrac as discrete data.

Background: Genetic diversity in human leukocyte antigen (HLA) alleles across populations is a significant risk factor for drug-induced severe cutaneous adverse reactions (SCARs), e.g., carbamazepine (CBZ)- and lamotrigine (LTG)-induced Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN). The present study aimed to investigate the frequency of different HLA alleles in Iranian patients with CBZ- and LTG-induced SJS/TEN.Methods: A case-control study was conducted from 2011 to 2018 at various hospitals affiliated with Shiraz University of Medical Sciences (Shiraz, Iran). A total of 31 patients receiving anticonvulsant drugs (CZB or LTG) were recruited and divided into two groups. The drug-induced group (n=14) included hospitalized patients due to CBZ- or LTG-induced SJS/TEN. The drug-tolerant group (n=17) included individuals receiving CBZ or LTG for at least three months with no adverse effects. In addition, 46 healthy individuals (control group) were recruited. The frequency of HLA-A, -B, and -DRB1 alleles in patients with CZB- or LTG-induced SJS/TEN was investigated. HLA typing was performed using the allele-specific polymerase chain reaction method. The Chi square test and Fisher’s exact test were used to determine a potential association between SJS/TEN and HLA alleles. P

BackgroundDonors other than matched siblings and low-intensity conditioning regimens are increasingly used in haematopoietic stem cell transplantation. We aimed to compare the relative risk of donor type and conditioning regimen intensity on the transplantation outcomes of in patients with sickle cell disease.MethodsFor this retrospective cohort study, we collected data from 90 US centres reported to the Center for International Blood and Marrow Transplant Research. Eligible patients were younger than 50 years, had genetically confirmed sickle cell disease (Hb SS) or sickle beta thalassemia (Hb Sβ), and underwent allogeneic haematopoietic cell transplantation between Jan 15, 2008, and Dec 28, 2017. We considered transplants from donor-recipient pairs matched at the allele-level (HLA-A, HLA-B, HLA-C, and HLA-DRB1), including HLA-matched sibling donors, haploidentical related donors, matched unrelated donors, or mismatched unrelated donors. The main outcome was event-free survival. The effect of donor type, conditioning regimen intensity (myeloablative, non-myeloablative, and reduced-intensity regimens), age (≤12 or 13-49 years), sex, performance score, comorbidity index, recipient cytomegalovirus serostatus, graft type (bone marrow, peripheral blood, or umbilical cord blood), and transplantation period (2008-12 and 2013-17) on outcomes was studied using Cox regression models.FindingsOf 996 patients with sickle cell disease and who underwent transplantation in 2008-17, 910 (91%) were included (558 [61%] patients had HLA-matched sibling donors, 137 [15%] haploidentical related donors, 111 [12%] matched unrelated donors, and 104 [11%] mismatched unrelated donors). The median follow-up was 36 months (IQR 18-60) after transplantation from HLA-matched siblings, 25 months (12-48) after transplantation from haploidentical related donors, 37 months (23-60) after transplantation from HLA-matched unrelated donors, and 47 months (24-72) after transplantation from mismatched unrelated donors. Event-free survival was worse in recipients aged 13 years or older than in those younger than 13 years (hazard ratio 1·74, 95% CI 1·24-2·45; p=0·0014) and in those who received a transplant from haploidentical related donors (5·30, 3·17-8·86; p

A 40-year-old female of Indian origin underwent spousal donor ABO-incompatible (ABOi) kidney transplantation. She was diagnosed to have end-stage kidney disease, around 1 year before transplant and it was presumed to be chronic tubulointerstitial nephritis. The female was detected to have acute hepatitis B, 2 months before transplant. She was a highly-sensitized patient with a prior history of blood transfusion and multiparity. Single-antigen bead assay was positive pretransplant. The removal of anti-human leukocyte antigen donor-specific antibodies and anti-B antibodies in our patient was a multi-step process. Timely initiation of antiviral therapy is crucial to reduce viral load and make the patient fit for transplantation. Despite a multitude of risk factors, our patient underwent successful kidney transplantation with a baseline creatinine of 0.6 mg/dL and excellent graft function. [ABSTRACT FROM AUTHOR]

Background: Cases of subacute thyroiditis (SAT) after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination have been reported. A human leukocyte antigen (HLA) allele, HLA-B*35, appears to be involved in the pathogenesis of SAT. Case presentation: We conducted HLA typing of one patient with SAT and another with both SAT and Graves' disease (GD), which developed after SARS-CoV-2 vaccination. Patient 1, a 58-year-old Japanese man, was inoculated with a SARS-CoV-2 vaccine (BNT162b2; Pfizer, New York, NY, USA). He developed fever (38 °C), cervical pain, palpitations, and fatigue on day 10 after vaccination. Blood chemistry tests revealed thyrotoxicosis and elevated serum C-reactive protein (CRP) and slightly increased serum antithyroid-stimulating antibody (TSAb) levels. Thyroid ultrasonography revealed the characteristic findings of SAT. Patient 2, a 36-year-old Japanese woman, was inoculated twice with a SARS-CoV-2 vaccine (mRNA-1273; Moderna, Cambridge, MA, USA). She developed fever (37.8 °C) and thyroid gland pain on day 3 after the second vaccination. Blood chemistry tests revealed thyrotoxicosis and elevated serum CRP, TSAb, and antithyroid-stimulating hormone receptor antibody levels. Fever and thyroid gland pain persisted. Thyroid ultrasonography revealed the characteristic findings of SAT (i.e., slight swelling and a focal hypoechoic area with decreased blood flow). Prednisolone treatment was effective for SAT. However, thyrotoxicosis causing palpitations relapsed thereafter, for which thyroid scintigraphy with 99mtechnetium pertechnetate was conducted, and the patient was diagnosed with GD. Thiamazole treatment was then initiated, which led to improvement in symptoms. Conclusion: HLA typing revealed that both patients had the HLA-B*35:01, -C*04:01, and -DPB1*05:01 alleles. Only patient 2 had the HLA-DRB1*11:01 and HLA-DQB1*03:01 alleles. The HLA-B*35:01 and HLA-C*04:01 alleles appeared to be involved in the pathogenesis of SAT after SARS-CoV-2 vaccination, and the HLA-DRB1*11:01 and HLA-DQB1*03:01 alleles were speculated to be involved in the postvaccination pathogenesis of GD. [ABSTRACT FROM AUTHOR]

Allogeneic bone marrow transplantation (BMT) is curative therapy for the treatment of patients with severe aplastic anemia (SAA). However, several conditioning regimens can be used for BMT. We evaluated transplant conditioning regimens for BMT in SAA after HLA-matched sibling and unrelated donor BMT. For recipients of HLA-matched sibling donor transplantation (n = 955), fludarabine (Flu)/cyclophosphamide (Cy)/antithymocyte globulin (ATG) or Cy/ATG led to the best survival. The 5-year probabilities of survival with Flu/Cy/ATG, Cy/ATG, Cy ± Flu, and busulfan/Cy were 91%, 91%, 80%, and 84%, respectively (P = .001). For recipients of 8/8 and 7/8 HLA allele-matched unrelated donor transplantation (n = 409), there were no differences in survival between regimens. The 5-year probabilities of survival with Cy/ATG/total body irradiation 200 cGy, Flu/Cy/ATG/total body irradiation 200 cGy, Flu/Cy/ATG, and Cy/ATG were 77%, 80%, 75%, and 72%, respectively (P = .61). Rabbit-derived ATG compared with equine-derived ATG was associated with a lower risk of grade II to IV acute graft-versus-host disease (GVHD) (hazard ratio [HR], 0.39; P < .001) but not chronic GVHD. Independent of conditioning regimen, survival was lower in patients aged >30 years after HLA-matched sibling (HR, 2.74; P < .001) or unrelated donor (HR, 1.98; P = .001) transplantation. These data support Flu/Cy/ATG and Cy/ATG as optimal regimens for HLA-matched sibling BMT. Although survival after an unrelated donor BMT did not differ between regimens, use of rabbit-derived ATG may be preferred because of lower risks of acute GVHD.

The human leukocyte antigen (HLA) genes are extremely polymorphic and are useful molecular markers to make inferences about human population history. However, the accuracy of the estimation of genetic diversity at HLA loci very much depends on the technology used to characterize HLA alleles; high-resolution genotyping of long-range HLA gene products improves the assessment of HLA population diversity as well as other population parameters compared to lower resolution typing methods. In this study we examined allelic and haplotype HLA diversity in a large healthy European American population sourced from the UCSF-DNA bank. A high-resolution next-generation sequencing method was applied to define non-ambiguous 3- and 4-field alleles at the HLA-A, HLA-C, HLA-B, HLA-DRB1, HLA-DRB3/4/5, HLA-DQA1, HLA-DQB1, HLA-DPA1, and HLA-DPB1 loci in samples provided by 2248 unrelated individuals. A number of population parameters were examined including balancing selection and various measurements of linkage disequilibrium were calculated. There were no detectable deviations from Hardy-Weinberg proportions at HLA-A, HLA-DRB1, HLA-DQA1 and HLA-DQB1. For the remaining loci moderate and significant deviations were detected at HLA-C, HLA-B, HLA-DRB3/4/5, HLA-DPA1 and HLA-DPB1 loci mostly from population substructures. Unique 4-field associations were observed among alleles at 2 loci and haplotypes extending large intervals that were not apparent in results obtained using testing methodologies with limited sequence coverage and phasing. The high diversity at HLA-DPA1 results from detection of intron variants of otherwise well conserved protein sequences. It may be speculated that divergence in exon sequences may be negatively selected. Our data provides a valuable reference source for future population studies that may allow for precise fine mapping of coding and non-coding sequences determining disease susceptibility and allo-immunogenicity.

Allogeneic hematopoietic cell transplantation involves consideration of both donor and recipient characteristics to guide the selection of a suitable graft. Sufficient high-resolution donor-recipient HLA match is of primary importance in transplantation with adult unrelated donors, using conventional graft-versus-host disease prophylaxis. In cord blood transplantation, optimal unit selection requires consideration of unit quality, cell dose and HLA-match. In this summary, the National Marrow Donor Program (NMDP) and the Center for International Blood and Marrow Transplant Research, jointly with the NMDP Histocompatibility Advisory Group, provide evidence-based guidelines for optimal selection of unrelated donors and cord blood units.

Kawasaki disease (KD) is a pediatric vasculitis caused by an unknown trigger in genetically susceptible children. The incidence varies widely across genetically diverse populations. Several associations with HLA Class I alleles have been reported in single cohort studies. Using a genetic approach, from the nine single nucleotide variants (SNVs) associated with KD susceptibility in children of European descent, we identified SNVs near the HLA-C (rs6906846) and HLA-B genes (rs2254556) whose association was replicated in a Japanese descent cohort (rs6906846 p = 0.01, rs2254556 p = 0.005). The risk allele (A at rs6906846) was also associated with HLA-C*07:02 and HLA-C*04:01 in both US multi-ethnic and Japanese cohorts and HLA-C*12:02 only in the Japanese cohort. The risk A-allele was associated with eight non-conservative amino acid substitutions (amino acid positions); Asp or Ser (9), Arg (14), Ala (49), Ala (73), Ala (90), Arg (97), Phe or Ser (99), and Phe or Ser (116) in the HLA-C peptide binding groove that binds peptides for presentation to cytotoxic T cells (CTL). This raises the possibility of increased affinity to a "KD peptide" that contributes to the vasculitis of KD in genetically susceptible children.

The 17th International HLA and Immunogenetics Workshop (IHIW) conducted a project entitled "The Study of Haplotypes in Families by NGS HLA". We investigated the HLA haplotypes of 1017 subjects in 263 nuclear families sourced from five US clinical immunogenetics laboratories, primarily as part of the evaluation of related donor candidates for hematopoietic stem cell and solid organ transplantation. The parents in these families belonged to five broad groups - African (72 parents), Asian (115), European (210), Hispanic (118) and "Other" (11). High-resolution HLA genotypes were generated for each subject using next-generation sequencing (NGS) HLA typing systems. We identified the HLA haplotypes in each family using HaplObserve, software that builds haplotypes in families by reviewing HLA allele segregation from parents to children. We calculated haplotype frequencies within each broad group, by treating the parents in each family as unrelated individuals. We also calculated standard measures of global linkage disequilibrium (LD) and conditional asymmetric LD for each ethnic group, and used untruncated and two-field allele names to investigate LD patterns. Finally we demonstrated the utility of consensus DNA sequences in identifying novel variants, confirming them using HLA allele segregation at the DNA sequence level.

HLA-DP mismatched allogeneic hematopoietic stem cell transplantation (allo-HCT) is associated with increased risk of aGVHD and decreased risk of relapse with no effects on overall survival (OS). It has been proposed that CMV-reactivation induces expression of HLA-DP molecules on GVHD target tissues by releasing inflammatory cytokines. We hypothesized that the increased GVHD incidence in HLA-DP mismatched allo-SCTs correlates with recipient CMV serostatus or CMV reactivation. In addition, CMV reactivation is associated with increased risk of GVHD with an unknown mechanism. Here, we analyzed the association between HLA-DPB1 and CMV reactivation on cumulative incidence of aGVHD and relapse as well as OS in 613 patients with AML and MDS who underwent matched related or unrelated allo-HCT at MD Anderson Cancer Center from 2005 to 2011. In multivariable analysis, HLA-DPB1 mismatching was associated with increased risk of aGVHD (hazard ratio (HR): 1.53, P

We conducted a multicenter pilot investigation of the safety and feasibility of bone marrow transplantation (BMT) in adults with severe sickle cell disease (SCD) (NCT 01565616) using a reduced toxicity preparative regimen of busulfan (13.2 mg/kg), fludarabine (175 mg/m2 ) and thymoglobulin (6 mg/kg) and cyclosporine or tacrolimus and methotrexate for graft-vs-host disease (GVHD) prophylaxis. Twenty-two patients (median age 22 years; range 17-36) were enrolled at eight centers. Seventeen patients received marrow from an HLA-identical sibling donor and five patients received marrow from an 8/8 HLA-allele matched unrelated donor. Before BMT, patients had stroke, acute chest syndrome, recurrent pain events, were receiving regular red blood cell transfusions, or had an elevated tricuspid regurgitant jet (TRJ) velocity, which fulfilled eligibility criteria. Four patients developed grades II-III acute GVHD (18%) and six developed chronic GVHD (27%) that was moderate in two and severe in one patient. One patient died of intracranial hemorrhage and one of GVHD. Nineteen patients had stable donor chimerism, 1-year post-transplant. One patient who developed secondary graft failure survives disease-free after a second BMT. The one-year overall survival and event-free survival (EFS) are 91% (95% CI 68%-98%) and 86% (95% CI, 63%-95%), respectively, and 3-year EFS is 82%. Statistically significant improvements in the pain interference and physical function domains of health-related quality of life were observed. The study satisfied the primary endpoint of 1-year EFS ≥70%. This regimen is being studied in a prospective clinical trial comparing HLA-matched donor BMT with standard of care in adults with severe SCD (NCT02766465).

The 17th International HLA and Immunogenetics Workshop (IHIW) organizers conducted a Pilot Study (PS) in which 13 laboratories (15 groups) participated to assess the performance of the various sequencing library preparation protocols, NGS platforms and software in use prior to the workshop. The organizers sent 50 cell lines to each of the 15 groups, scored the 15 independently generated sets of NGS HLA genotyping data, and generated "consensus" HLA genotypes for each of the 50 cell lines. Proficiency Testing (PT) was subsequently organized using four sets of 24 cell lines, selected from 48 of 50 PS cell lines, to validate the quality of NGS HLA typing data from the 34 participating IHIW laboratories. Completion of the PT program with a minimum score of 95% concordance at the HLA-A, HLA-B, HLA-C, HLA-DRB1 and HLA-DQB1 loci satisfied the requirements to submit NGS HLA typing data for the 17th IHIW projects. Together, these PS and PT efforts constituted the 17th IHIW Quality Control project. Overall PT concordance rates for HLA-A, HLA-B, HLA-C, HLA-DPA1, HLA-DPB1, HLA-DQA1, HLA-DQB1, HLA-DRB1, HLA-DRB3, HLA-DRB4 and HLA-DRB5 were 98.1%, 97.0% and 98.1%, 99.0%, 98.6%, 98.8%, 97.6%, 96.0%, 99.1%, 90.0% and 91.7%, respectively. Across all loci, the majority of the discordance was due to allele dropout. The high cost of NGS HLA genotyping per experiment likely prevented the retyping of initially failed HLA loci. Despite the high HLA genotype concordance rates of the software, there remains room for improvement in the assembly of more accurate consensus DNA sequences by NGS HLA genotyping software.

The determination of null- or low-expressed HLA alleles is clinically relevant in both hematopoietic stem cell transplantation and solid organ transplantation. We studied the expression level of a questionable (Q) HLA-B*38:68Q allele, which carries a 9-nucleotide (nt) deletion at codon 230-232 in exon 4 of HLA-B*38:01:01:01 using CRISPR/Cas9 gene editing technology. CRISPR/Cas9 gene editing of HLA-B*38:01:01:01 homozygous EBV B cell line resulted in one HLA-B*38:68Q/B*38:01:01:01 heterozygous and one HLA-B*38:68Q homozygous clone. Flow cytometric analysis of monoclonal anti-Bw4 antibody showed the protein expression of HLA-B*38:01:01:01 in homozygous cells was 2.2 fold higher than HLA-B*38:68Q/B*38:01:01:01 heterozygous cells, and the expression of HLA-B*38:68Q/B*38:01:01:01 heterozygous cells was over 2.0 fold higher than HLA-B*38:68Q homozygous cells. The HLA-B*38:68Q expression was further confirmed using anti-B38 polyclonal antibody. Similarly, the expression of the HLA-B*38:01:01:01 homozygous cells was 1.5 fold higher than that of HLA-B*38:68Q/B*38:01:01:01 heterozygous cells, and the HLA-B*38:68Q/B*38:01:01:01 heterozygous cells was over 1.6 fold higher than that of HLA-B*38:68Q homozygous cells. The treatment of HLA-B*38:68Q homozygous cells with IFN-γ significantly increased its expression. In conclusion, we demonstrate that HLA-B*38:68Q is a low-expressing HLA allele. The CRISPR/Cas9 technology is a useful tool to induce precise gene editing in HLA genes to enable the characterization of HLA gene variants on expression and function.

Matching of human leukocyte antigen (HLA) genes is critically important in hematopoietic stem cell transplantation (HSCT). HLA genes are highly polymorphic and HLA matching has historically been limited by technologies that are unable to unambiguously determine HLA genotypes. Next generation DNA sequencing (NGS) overcomes these limitations by enabling near full-gene sequences with phase determination for heterozygous alleles. Here we examine the efficacy and utility of HLA-NGS in the clinical setting. In a 54-sample validation study and 955 patient samples subsequently tested using HLA-NGS, we observed significant improvement in the ability to unambiguously identify HLA genotypes in both the validation (97.3%) and clinical (97.4%) sample cohorts compared to previous standard-of care HLA genotyping methods. We modeled the clinical impact of this improved diagnostic ability by comparing National Marrow Donor Program (NMDP) search results for 56 patients using HLA-NGS genotypes and simulated standard-of-care HLA genotypes. Surprisingly, we observed significant differences in 7.1% of NMDP searches, with improved unambiguous HLA genotyping correlating with improved prediction of finding well-matched and partially-matched unrelated HSCT donors. These data demonstrate that HLA-NGS can provide highly accurate and unambiguous HLA genotyping that facilitates donor selection for allogeneic HSCT.

DNA sequence-based typing at the HLA-A, -B, -C, -DPB1, -DQA1, -DQB1, and -DRB1 loci was performed on 496 healthy adult donors from San Diego, California, to characterize allele frequencies in support of studies of T cell responses to common allergens. Deviations from Hardy Weinberg proportions were detected at each locus except A and C. Several alleles were found in more than 15% of individuals, including the class II alleles DPB1∗02:01, DPB1∗04:01, DQA1∗01:02, DQA1∗05:01, DQB1∗03:01, and the class I allele A∗02:01. Genotype data will be available in the Allele Frequencies Net Database (AFND 3562).