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Kramer CSM, Bezstarosti S, Franke-van Dijk MEI, Vergunst M, Roelen DL, Uyar-Mercankaya M, Voogt-Bakker KH, Heidt S. Antibody verification of HLA class I and class II eplets by human monoclonal HLA antibodies. HLA 2024; 103:e15345. [PMID: 38239050 DOI: 10.1111/tan.15345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 12/11/2023] [Accepted: 12/29/2023] [Indexed: 01/23/2024]
Abstract
In solid organ transplantation, formation of de novo donor-specific HLA antibodies is induced by mismatched eplets on donor HLA molecules. While several studies have shown a strong correlation between the number of eplet mismatches and inferior outcomes, not every eplet mismatch is immunogenic. Eplets are theoretically defined entities, necessitating formal proof that they can be recognised and bound by antibodies. This antibody verification is pivotal to ensure that clinically relevant eplets are considered in studies on molecular matching. Recombinant human HLA-specific monoclonal antibodies (mAbs) were generated from HLA-reactive B cell clones isolated from HLA immunised individuals using recombinant HLA molecules. Subsequently, the reactivity patterns of the mAbs obtained from single antigen bead assay were analysed using HLA-EMMA software to identify single or configurations of solvent accessible amino acids uniquely present on the reactive HLA alleles and were mapped to eplets. Two HLA class I and seven HLA class II-specific human mAbs were generated from four individuals. Extensive mAb reactivity analysis, led to antibody verification of three HLA-DR-specific eplets, and conversion of five eplets (one HLA-A, one HLA-B, two HLA-DR, and one HLA-DP), from provisionally verified to truly antibody-verified. Finally, one HLA-DQ-specific eplet was upgraded from level A2 to level A1 verification evidence. The generation of recombinant human HLA-specific mAbs with different specificities contributes significantly to the antibody verification of eplets and therefore is instrumental for implementation of eplet matching in the clinical setting.
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Affiliation(s)
- Cynthia S M Kramer
- Department of Immunology, Leiden University Medical Center, Leiden, The Netherlands
| | - Suzanne Bezstarosti
- Department of Immunology, Leiden University Medical Center, Leiden, The Netherlands
- Department of Nephrology, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Manon Vergunst
- Department of Immunology, Leiden University Medical Center, Leiden, The Netherlands
| | - Dave L Roelen
- Department of Immunology, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Kim H Voogt-Bakker
- Department of Immunology, Leiden University Medical Center, Leiden, The Netherlands
| | - Sebastiaan Heidt
- Department of Immunology, Leiden University Medical Center, Leiden, The Netherlands
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2
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Seeking Standardized Definitions for HLA-incompatible Kidney Transplants: A Systematic Review. Transplantation 2023; 107:231-253. [PMID: 35915547 DOI: 10.1097/tp.0000000000004262] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND There is no standard definition for "HLA incompatible" transplants. For the first time, we systematically assessed how HLA incompatibility was defined in contemporary peer-reviewed publications and its prognostic implication to transplant outcomes. METHODS We combined 2 independent searches of MEDLINE, EMBASE, and the Cochrane Library from 2015 to 2019. Content-expert reviewers screened for original research on outcomes of HLA-incompatible transplants (defined as allele or molecular mismatch and solid-phase or cell-based assays). We ascertained the completeness of reporting on a predefined set of variables assessing HLA incompatibility, therapies, and outcomes. Given significant heterogeneity, we conducted narrative synthesis and assessed risk of bias in studies examining the association between death-censored graft failure and HLA incompatibility. RESULTS Of 6656 screened articles, 163 evaluated transplant outcomes by HLA incompatibility. Most articles reported on cytotoxic/flow T-cell crossmatches (n = 98). Molecular genotypes were reported for selected loci at the allele-group level. Sixteen articles reported on epitope compatibility. Pretransplant donor-specific HLA antibodies were often considered (n = 143); yet there was heterogeneity in sample handling, assay procedure, and incomplete reporting on donor-specific HLA antibodies assignment. Induction (n = 129) and maintenance immunosuppression (n = 140) were frequently mentioned but less so rejection treatment (n = 72) and desensitization (n = 70). Studies assessing death-censored graft failure risk by HLA incompatibility were vulnerable to bias in the participant, predictor, and analysis domains. CONCLUSIONS Optimization of transplant outcomes and personalized care depends on accurate HLA compatibility assessment. Reporting on a standard set of variables will help assess generalizability of research, allow knowledge synthesis, and facilitate international collaboration in clinical trials.
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3
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Cardoso B, Wang J, Kiernan J, Dipchand AI. Eplet matching in pediatric heart transplantation: The SickKids experience. J Heart Lung Transplant 2022; 41:1470-1477. [DOI: 10.1016/j.healun.2022.06.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 06/11/2022] [Accepted: 06/29/2022] [Indexed: 11/16/2022] Open
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4
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Bezstarosti S, Bakker KH, Kramer CSM, de Fijter JW, Reinders MEJ, Mulder A, Claas FHJ, Heidt S. A Comprehensive Evaluation of the Antibody-Verified Status of Eplets Listed in the HLA Epitope Registry. Front Immunol 2022; 12:800946. [PMID: 35154076 PMCID: PMC8831796 DOI: 10.3389/fimmu.2021.800946] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Accepted: 12/30/2021] [Indexed: 01/09/2023] Open
Abstract
Matching strategies based on HLA eplets instead of HLA antigens in solid organ transplantation may not only increase the donor pool for highly sensitized patients, but also decrease the incidence of de novo donor-specific antibody formation. However, since not all eplets are equally capable of inducing an immune response, antibody verification is needed to confirm their ability to be bound by antibodies, such that only clinically relevant eplets are considered. The HLA Epitope Registry has documented all theoretically defined HLA eplets along with their antibody verification status and has been the foundation for many clinical studies investigating eplet mismatch in transplantation. The verification methods for eplets in the Registry range from polyclonal sera from multi- and uni-parous women to murine and human monoclonal antibodies (mAbs), and antibodies purified by adsorption and elution from sera of HLA immunized individuals. The classification of antibody verification based on different methods for validation is problematic, since not all approaches represent the same level of evidence. In this study, we introduce a classification system to evaluate the level of evidence for the antibody-verified status of all eplets in the HLA Epitope Registry. We demonstrate that for a considerable number of eplets, the antibody-verified status is solely based on polyclonal serum reactivity of multiparous women or on reactivity of murine mAbs. Furthermore, we noted that a substantial proportion of patient sera analyses and human mAb data presented in the HLA Epitope Registry Database has never been published in a peer-reviewed journal. Therefore, we tested several unpublished human HLA-specific mAbs by luminex single antigen beads assay to analyze their HLA reactivity for eplet antibody verification. Although the majority of analyzed mAbs indeed verified their assigned eplets, this was not the case for a number of eplets. This comprehensive overview of evidence for antibody verification of eplets in the HLA Epitope Registry is instrumental for future investigations towards eplet immunogenicity and clinical studies considering antibody-verified eplet mismatch in transplantation and warrants further standardization of antibody verification using high quality data.
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Affiliation(s)
- Suzanne Bezstarosti
- Department of Immunology, Leiden University Medical Center, Leiden, Netherlands.,Department of Internal Medicine (Nephrology), Leiden University Medical Center, Leiden, Netherlands
| | - Kim H Bakker
- Department of Immunology, Leiden University Medical Center, Leiden, Netherlands
| | - Cynthia S M Kramer
- Department of Immunology, Leiden University Medical Center, Leiden, Netherlands
| | - Johan W de Fijter
- Department of Internal Medicine (Nephrology), Leiden University Medical Center, Leiden, Netherlands
| | - Marlies E J Reinders
- Department of Internal Medicine, Erasmus Medical Center Transplantation Institute, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Arend Mulder
- Department of Immunology, Leiden University Medical Center, Leiden, Netherlands
| | - Frans H J Claas
- Department of Immunology, Leiden University Medical Center, Leiden, Netherlands.,Eurotransplant Reference Laboratory, Leiden, Netherlands
| | - Sebastiaan Heidt
- Department of Immunology, Leiden University Medical Center, Leiden, Netherlands.,Eurotransplant Reference Laboratory, Leiden, Netherlands
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5
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Molecular disparity in human leukocyte antigens is associated with outcomes in haploidentical stem cell transplantation. Blood Adv 2021; 4:3474-3485. [PMID: 32726398 DOI: 10.1182/bloodadvances.2019000797] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 06/19/2020] [Indexed: 02/06/2023] Open
Abstract
Haploidentical donors are increasingly used for patients requiring hematopoietic stem cell transplantation (HSCT). Although several factors have been associated with transplant outcomes, the impact of HLA disparity in haploidentical HSCT (haplo-HSCT) remains unclear. We investigated the impact of HLA disparity quantified by mismatched eplets (ME) load of each HLA locus on the clinical outcome of 278 consecutive haploidentical transplants. Here, we demonstrated that the degree of HLA molecular mismatches, at individual HLA loci, may be relevant to clinical outcome in the haplo-HSCT. A significantly better overall survival was associated with higher ME load from HLA-A (hazard ratio [HR], 0.97; 95% confidence interval [CI], 0.95-0.99; P = .003) and class I loci (HR, 0.99; 95% CI, 0.97-0.99; P = .045) in the host-versus-graft direction. The apparent survival advantage of HLA-A ME was primarily attributed to reduced risk in relapse associated with an increase in HLA-A ME load (subdistribution HR, 0.95; 95% CI, 0.92-0.98; P = .004). Furthermore, we have identified an association between the risk of grade 3-4 acute graft-versus-host disease (GVHD) and a higher ME load at HLA-B and class I loci in graft-versus-host (GVH) direction. Additionally, GVH nonpermissive HLA-DPB1 mismatch defined by T-cell epitope grouping was significantly associated with relapse protection (subdistribution HR, 0.19; 95% CI, 0.06-0.59; P = .004) without a concurrent increase in GVHD. These findings indicate that alloreactivity generated by HLA disparity at certain HLA loci is associated with transplant outcomes, and ME analysis of individual HLA loci might assist donor selection and risk stratification in haplo-HSCT.
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6
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Schawalder L, Hönger G, Kleiser M, van Heck MR, van de Pasch LAL, Vendelbosch S, Rozemuller EH, Schaub S. Development of an immunogenicity score for HLA-DQ eplets: A conceptual study. HLA 2020; 97:30-43. [PMID: 33068062 PMCID: PMC7756751 DOI: 10.1111/tan.14110] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 10/01/2020] [Accepted: 10/10/2020] [Indexed: 12/27/2022]
Abstract
Eplets are defined as distinct amino acid configurations on the surface of HLA molecules. The aim of this study was to estimate the immunogenicity of HLA‐DQ eplets in a cohort of 221 pregnancies with HLA‐DQ mismatches. We defined the immunogenicity of an eplet by the frequency of antibody responses against it. Around 90% of all listed DQB1 or DQA1 eplets were at least five times mismatched and thus included for the calculation of their immunogenicity. The DQB1 eplets with the five highest immunogenicity scores were 55PP, 52PR, 52PQ, 85VG and 45EV; 25% of all DQB1 eplets were not reacting. The DQA1 eplets with the five highest immunogenicity scores were 25YS, 47QL, 55RR, 187T and 18S; 17% of all DQA1 eplets were not reacting. The immunogenicity score had a slightly higher area under the curve to predict development of child‐specific antibodies than various molecular mismatch scores (eg, eplet mismatch load, amino acid mismatch load). Overlapping eplets were identified as a barrier to unambiguously assign the immunogenicity score based on HLA antibody reaction patterns. In this conceptual study, we explored the immunogenicity of HLA‐DQ eplets and created a map of potentially immunogenic regions on HLA‐DQ molecules, which requires validation in clinical transplant cohorts.
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Affiliation(s)
- Lara Schawalder
- Clinic for Transplantation Immunology and Nephrology, University Hospital Basel, Basel, Switzerland
| | - Gideon Hönger
- Clinic for Transplantation Immunology and Nephrology, University Hospital Basel, Basel, Switzerland.,Transplantation Immunology, Department of Biomedicine, University of Basel, Basel, Switzerland.,HLA-Diagnostics and Immungenetics, Department of Laboratory Medicine, University Hospital Basel, Basel, Switzerland
| | - Marc Kleiser
- HLA-Diagnostics and Immungenetics, Department of Laboratory Medicine, University Hospital Basel, Basel, Switzerland
| | | | | | | | | | - Stefan Schaub
- Clinic for Transplantation Immunology and Nephrology, University Hospital Basel, Basel, Switzerland.,Transplantation Immunology, Department of Biomedicine, University of Basel, Basel, Switzerland.,HLA-Diagnostics and Immungenetics, Department of Laboratory Medicine, University Hospital Basel, Basel, Switzerland
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7
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Heidt S, Claas FHJ. Not all HLA epitope mismatches are equal. Kidney Int 2020; 97:653-655. [PMID: 32200859 DOI: 10.1016/j.kint.2019.12.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 12/19/2019] [Indexed: 02/06/2023]
Abstract
The future of HLA matching in solid organ transplantation lies in epitope matching. The article by Sapir-Pichhadze et al. provides indirect evidence that there is a difference in immunogenicity between antibody-verified versus non-verified eplets. However, this difference was less clear for HLA class II, showing the need for additional efforts to identify truly immunogenic HLA class II epitope mismatches.
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Affiliation(s)
- Sebastiaan Heidt
- Eurotransplant Reference Laboratory, Leiden University Medical Center, Leiden, the Netherlands.
| | - Frans H J Claas
- Eurotransplant Reference Laboratory, Leiden University Medical Center, Leiden, the Netherlands
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8
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Osorio-Jaramillo E, Haasnoot GW, Kaider A, Schaefer AK, Haberl T, Goekler J, Angleitner P, Moayedifar R, Zuckermann A, Fischer GF, Laufer G, Claas FHJ, Aliabadi-Zuckermann AZ. Molecular-level HLA mismatch is associated with rejection and worsened graft survival in heart transplant recipients - a retrospective study. Transpl Int 2020; 33:1078-1088. [PMID: 32441827 PMCID: PMC7540475 DOI: 10.1111/tri.13657] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 03/10/2020] [Accepted: 05/15/2020] [Indexed: 01/06/2023]
Abstract
The aim was to evaluate the association of molecular‐level human leukocyte antigen (HLA) mismatching with post‐transplant graft survival, rejection, and cardiac allograft vasculopathy (CAV). We retrospectively analyzed all primary cardiac transplant recipients between 01/1984‐06/2016. 1167 patients fulfilled inclusion criteria and had HLA typing information available. In 312 donor‐recipient pairs, typing at serological split antigen level was available. We used the Epitope MisMatch Algorithm to calculate the number of amino acid differences in antibody‐verified HLA eplets (amino acid mismatch load (AAMM)) between donor and recipient. Patients with a higher HLA‐DR AAMM load had inferior 1‐year graft survival (hazard ratio [HR], 1.14; 95% confidence interval [CI], 1.01–1.28). The HLA‐AB AAMM load showed no impact on graft survival. In the subgroup with available split‐level information, we observed an inferior graft survival for a higher HLA‐DR AAMM load 3 months after transplantation (HR, 1.22; 95% CI, 1.04–1.44) and a higher risk for rejection for an increasing HLA‐AB (HR, 1.70; 95% CI, 1.29–2.24) and HLA‐DR (HR, 1.32; 95% CI, 1.09–1.61) AAMM load. No impact on the development of CAV was found. Molecular‐level HLA mismatch analysis could serve as a tool for risk stratification after heart transplantation and might take us one step further into precision medicine.
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Affiliation(s)
| | - Geert W Haasnoot
- Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands
| | - Alexandra Kaider
- Center for Medical Statistics, Informatics and Intelligent Systems, Medical University of Vienna, Vienna, Austria
| | | | - Thomas Haberl
- Division of Cardiac Surgery, Medical University of Vienna, Vienna, Austria
| | - Johannes Goekler
- Division of Cardiac Surgery, Medical University of Vienna, Vienna, Austria
| | - Philipp Angleitner
- Division of Cardiac Surgery, Medical University of Vienna, Vienna, Austria
| | - Roxana Moayedifar
- Division of Cardiac Surgery, Medical University of Vienna, Vienna, Austria
| | - Andreas Zuckermann
- Division of Cardiac Surgery, Medical University of Vienna, Vienna, Austria
| | - Gottfried F Fischer
- Department for Blood Group Serology and Transfusion Medicine, Medical University of Vienna, Vienna, Austria
| | - Guenther Laufer
- Division of Cardiac Surgery, Medical University of Vienna, Vienna, Austria
| | - Frans H J Claas
- Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands.,Laboratory of Experimental Medicine and Pediatrics, University of Antwerp, Antwerp, Belgium
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9
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Vayntrub TA, Mack SJ, Fernandez-Viña MA. Preface: 17th International HLA and Immunogenetics Workshop. Hum Immunol 2020; 81:52-58. [PMID: 32051104 DOI: 10.1016/j.humimm.2020.01.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Tamara A Vayntrub
- Histocompatibility, Immunogenetics, and Disease Profiling Laboratory, Stanford Blood Center, Palo Alto, CA, USA.
| | - Steven J Mack
- Center for Genetics, Children's Hospital Oakland Research Institute, Oakland, CA, USA.
| | - Marcelo A Fernandez-Viña
- Histocompatibility, Immunogenetics, and Disease Profiling Laboratory, Stanford Blood Center, Palo Alto, CA, USA; Department of Pathology, Stanford University Medical Center, Stanford, CA, USA.
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10
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Reindl-Schwaighofer R, Heinzel A, Gualdoni GA, Mesnard L, Claas FHJ, Oberbauer R. Novel insights into non-HLA alloimmunity in kidney transplantation. Transpl Int 2019; 33:5-17. [PMID: 31650645 PMCID: PMC6972536 DOI: 10.1111/tri.13546] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2019] [Revised: 08/26/2019] [Accepted: 10/23/2019] [Indexed: 12/14/2022]
Abstract
Recognition of non‐self structures on donor cells represents the main immunological barrier in solid organ transplantation. The human leukocyte antigens (HLA) are considered the most important non‐self (allo)antigens in transplantation. Long‐term graft attrition is mainly caused by the formation of alloreactive antibodies that are directed against non‐self structures (i.e., epitopes) on cell surface proteins. Recently published data provided evidence for a similar importance of non‐HLA mismatches between donors and recipients in acute rejection as well as long‐term kidney allograft survival. These data suggest a broader concept of immunological non‐self that goes beyond HLA incompatibility and expands the current concept of polymorphic non‐self epitopes on cell surface molecules from HLA to non‐HLA targets. Amino acid substitutions caused by single nucleotide variants in protein‐coding genes or complete loss of gene expression represent the basis for polymorphic residues in both HLA and non‐HLA molecules. To better understand these novel insights in non‐HLA alloimmunity, we will first review basic principles of the alloimmune response with a focus on the HLA epitope concept in donor‐specific antibody formation before discussing key publications on non‐HLA antibodies.
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Affiliation(s)
- Roman Reindl-Schwaighofer
- Division of Nephrology and Dialysis, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Andreas Heinzel
- Division of Nephrology and Dialysis, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Guido A Gualdoni
- Division of Nephrology and Dialysis, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Laurent Mesnard
- Sorbonne Université, Urgences Néphrologiques et Transplantation Rénale, Assistance Publique-Hôpitaux de Paris (APHP), Hôpital Tenon, Paris, France
| | - Frans H J Claas
- Department of Immunohematology and Blood Transfusion, Leiden University Medical Centre, Leiden, The Netherlands
| | - Rainer Oberbauer
- Division of Nephrology and Dialysis, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
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