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Khalili M, Famure O, Minkovich M, Tinckam KJ, Kim SJ. Selective Elimination and Rationalization of Cell-based Assays in Deceased Donor Kidney Transplant Crossmatching. Transplant Direct 2024; 10:e1603. [PMID: 38464424 PMCID: PMC10923350 DOI: 10.1097/txd.0000000000001603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 12/30/2023] [Accepted: 01/24/2024] [Indexed: 03/12/2024] Open
Abstract
Background While there is increasing reliance on a negative virtual crossmatch to proceed with deceased donor kidney transplantation, a flow cytometry crossmatch (FCXM) is still usually performed after the transplant has already occurred. Our center has eliminated pretransplant physical crossmatches for most patients, and since 2018, we have eliminated the systematic performance of posttransplant FCXMs. Methods We studied all deceased donor kidney transplants in our program between June 1, 2018, and March 31, 2021, to evaluate the impact of eliminating retrospective FCXMs on resource utilization and graft outcomes (ie, the occurrence of antibody-mediated rejection [AMR] in the first 3-mo posttransplant). Results A total of 358 kidney transplants occurred during the study period, and approximately 70% of these transplants proceeded without the performance of any FCXM. Incidence rates of AMR were low (9.63 per 1000 person-months), which compared favorably with the incidence rate of AMR during the 3-y period preceding the policy (4.82 per 1000 person-months, P = 0.21). Conclusions Our results suggest that moving away from retrospective FCXM and relying exclusively on the virtual crossmatch is safe and efficient for kidney allocation.
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Affiliation(s)
- Myriam Khalili
- Ajmera Transplant Centre, Toronto General Hospital, University Health Network, Toronto, ON, Canada
- Division of Nephrology, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Olusegun Famure
- Ajmera Transplant Centre, Toronto General Hospital, University Health Network, Toronto, ON, Canada
| | - Michelle Minkovich
- Ajmera Transplant Centre, Toronto General Hospital, University Health Network, Toronto, ON, Canada
| | - Kathryn J Tinckam
- Ajmera Transplant Centre, Toronto General Hospital, University Health Network, Toronto, ON, Canada
- Division of Nephrology, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Sang Joseph Kim
- Ajmera Transplant Centre, Toronto General Hospital, University Health Network, Toronto, ON, Canada
- Division of Nephrology, University Health Network, University of Toronto, Toronto, ON, Canada
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Hod-Dvorai R, Philogene MC, Timofeeva O, Gimferrer I, Dunckley H, Greenshields A, Jindra P. Utilizing proficiency testing survey data to create advanced educational content: the virtual crossmatch challenge model. Front Genet 2023; 14:1256498. [PMID: 37811147 PMCID: PMC10552184 DOI: 10.3389/fgene.2023.1256498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 09/11/2023] [Indexed: 10/10/2023] Open
Abstract
Proficiency testing (PT) surveys include data from laboratories across the world and are ideal for creating advanced educational content, beyond just consensus grading. Educational challenges provide a unique opportunity to probe common laboratory practices and risk assessment, especially in cases where there is no "analyte" tested. Human leukocyte antigen (HLA) compatibility evaluation between donor and recipient pairs has been traditionally assessed using T-cell and B-cell physical crossmatches. However, advancements in our ability to identify and characterize HLA antibodies using solid phase assays, in combination with changing deceased donor allocation schemes and improved HLA typing, have shifted the paradigm from performing physical crossmatches to the use of the virtual crossmatch (VXM). VXM is a compatibility assessment relying on the interpretation of pre-transplant HLA laboratory data and as such, it is not an "analyte". However, VXM results are used in clinical decision-making. The VXM assessment depends on patient characteristics as well as laboratory and transplant center practices but must ensure safe transplantation outcomes while maintaining equity in access to transplantation. In this manuscript, we describe the American Society for Histocompatibility and Immunogenetics (ASHI) PT Educational VXM Challenge, as a model for creating educational content using PT survey data. We discuss the different components of the VXM Challenge and highlight major findings and learning points acquired from ASHI VXM Challenges performed between 2018-2022, such as the lack of correlation between the VXM and the physical crossmatch in the presence of low level donor-specific antibodies (DSA), or when the DSA were aimed against donor alleles that are not present on the antibody panel, and in the presence of an antibody to a shared eplet. Finally, we show that the VXM Educational Challenge serves as a valuable tool to highlight the strengths and pitfalls of the VXM assessment and reveals differences in testing and result interpretation among participating HLA laboratories.
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Affiliation(s)
- Reut Hod-Dvorai
- Department of Pathology, SUNY Upstate Medical University, Syracuse, NY, United States
| | - Mary Carmelle Philogene
- Department of Surgery, Virginia Commonwealth University Medical Center, Richmond, VA, United States
| | - Olga Timofeeva
- Department of Pathology, MedStar Georgetown University Hospital, Georgetown University Medical Center, Washington, DC, United States
| | - Idoia Gimferrer
- Department of Immunogenetics/HLA, BloodworksNW, Seattle, WA, United States
| | - Heather Dunckley
- New Zealand Transplantation and Immunogenetics Laboratory, New Zealand Blood Service, Auckland, New Zealand
| | | | - Peter Jindra
- Immune Evaluation Laboratory, Department of Surgery, Baylor College of Medicine, Houston, TX, United States
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Locke AF, Hickey M, Valenzuela NM, Butler C, Sosa R, Zheng Y, Gjertson D, Reed EF, Zhang Q. Virtual and Reality: An Analysis of the UCLA Virtual Crossmatch Exchanges. Transplantation 2023; 107:1776-1785. [PMID: 36944607 PMCID: PMC10358445 DOI: 10.1097/tp.0000000000004586] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 01/05/2023] [Accepted: 01/29/2023] [Indexed: 03/23/2023]
Abstract
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, UCLA's 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.
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Affiliation(s)
- Arlene F. Locke
- UCLA Immunogenetics Center, Department of Pathology and Laboratory Medicine, UCLA Health, Los Angeles, CA
| | - Michelle Hickey
- UCLA Immunogenetics Center, Department of Pathology and Laboratory Medicine, UCLA Health, Los Angeles, CA
| | - Nicole M. Valenzuela
- UCLA Immunogenetics Center, Department of Pathology and Laboratory Medicine, UCLA Health, Los Angeles, CA
| | - Carrie Butler
- UCLA Immunogenetics Center, Department of Pathology and Laboratory Medicine, UCLA Health, Los Angeles, CA
| | - Rebecca Sosa
- UCLA Immunogenetics Center, Department of Pathology and Laboratory Medicine, UCLA Health, Los Angeles, CA
| | - Ying Zheng
- UCLA Immunogenetics Center, Department of Pathology and Laboratory Medicine, UCLA Health, Los Angeles, CA
| | - David Gjertson
- UCLA Immunogenetics Center, Department of Pathology and Laboratory Medicine, UCLA Health, Los Angeles, CA
| | - Elaine F. Reed
- UCLA Immunogenetics Center, Department of Pathology and Laboratory Medicine, UCLA Health, Los Angeles, CA
| | - Qiuheng Zhang
- UCLA Immunogenetics Center, Department of Pathology and Laboratory Medicine, UCLA Health, Los Angeles, CA
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Puttarajappa CM, Tevar AD, Hoffman W, Degenholtz H, Schinstock CA, Gunabushanam V, Zeevi A, Xu Q, Hariharan S. Virtual crossmatch for deceased donor kidney transplantation in the United States: A survey of histocompatibility lab directors and transplant surgeons. Hum Immunol 2023; 84:214-223. [PMID: 36581507 PMCID: PMC9991979 DOI: 10.1016/j.humimm.2022.12.001] [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: 09/02/2022] [Revised: 11/22/2022] [Accepted: 12/20/2022] [Indexed: 12/28/2022]
Abstract
Virtual crossmatch (VXM) is used as an alternative to or in conjunction with a cell-based physical crossmatch (PXM) for assessing HLA (human leukocyte antigen) compatibility prior to deceased donor kidney transplantation (DDKT). Data on practice patterns and perceptions regarding VXM use in the US are limited. We performed a survey of US HLA directors and transplant surgeons regarding HLA testing and crossmatch strategies. 53 (56 %) HLA directors and 68 surgeons (representing ∼ 23 % of US transplant centers) completed the survey. Both groups agreed that VXM could reduce cold ischemia time (CIT), costs and improve allocation efficiency. VXM use increased following the 2021 kidney allocation change. Reducing CIT was the primary reason for favoring VXM over PXM. Preference for VXM reduced as candidates' panel reactive antibodies increased. Regulations, program policies and limitations of HLA technology were cited as important reasons for preferring PXM over VXM. Surgeons reported similar perceptions, but findings are limited by the low response rate. Finally, half the labs reported lacking specific protocols for VXM use. In conclusion, improved HLA technology and protocols along with changes to institutional procedures and policy regulations are needed for safer expansion of VXM in DDKT.
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Affiliation(s)
- Chethan M Puttarajappa
- Department of Medicine, Renal-Electrolyte Division, University of Pittsburgh, Pittsburgh, USA.
| | - Amit D Tevar
- Department of Surgery, University of Pittsburgh, Pittsburgh, USA
| | | | - Howard Degenholtz
- Department of Health Policy and Management, University of Pittsburgh, Pittsburgh, USA
| | | | | | - Adriana Zeevi
- Department of Pathology, University of Pittsburgh, Pittsburgh, USA
| | - Qingyong Xu
- Department of Pathology, University of Pittsburgh, Pittsburgh, USA
| | - Sundaram Hariharan
- Department of Medicine, Renal-Electrolyte Division, University of Pittsburgh, Pittsburgh, USA
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Puttarajappa CM, Hariharan S, Zhang X, Tevar A, Mehta R, Gunabushanam V, Sood P, Hoffman W, Mohan S. Early Effect of the Circular Model of Kidney Allocation in the United States. J Am Soc Nephrol 2023; 34:26-39. [PMID: 36302599 PMCID: PMC10101588 DOI: 10.1681/asn.2022040471] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 07/21/2022] [Accepted: 08/16/2022] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND In March 2021, the United States implemented a new kidney allocation system (KAS250) for deceased donor kidney transplantation (DDKT), which eliminated the donation service area-based allocation and replaced it with a system on the basis of distance from donor hospital to transplant center within/outside a radius of 250 nautical miles. The effect of this policy on kidney discards and logistics is unknown. METHODS We examined discards, donor-recipient characteristics, cold ischemia time (CIT), and delayed graft function (DGF) during the first 9 months of KAS250 compared with a pre-KAS250 cohort from the preceding 2 years. Changes in discards and CIT after the onset of COVID-19 and the implementation of KAS250 were evaluated using an interrupted time-series model. Changes in allocation practices (biopsy, machine perfusion, and virtual cross-match) were also evaluated. RESULTS Post-KAS250 saw a two-fold increase in kidneys imported from nonlocal organ procurement organizations (OPO) and a higher proportion of recipients with calculated panel reactive antibody (cPRA) 81%-98% (12% versus 8%; P <0.001) and those with >5 years of pretransplant dialysis (35% versus 33%; P <0.001). CIT increased (mean 2 hours), including among local OPO kidneys. DGF was similar on adjusted analysis. Discards after KAS250 did not immediately change, but we observed a statistically significant increase over time that was independent of donor quality. Machine perfusion use decreased, whereas reliance on virtual cross-match increased, which was associated with shorter CIT. CONCLUSIONS Early trends after KAS250 show an increase in transplant access to patients with cPRA>80% and those with longer dialysis duration, but this was accompanied by an increase in CIT and a suggestion of worsening kidney discards.
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Affiliation(s)
- Chethan M. Puttarajappa
- Department of Medicine, Renal-Electrolyte Division, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Sundaram Hariharan
- Department of Medicine, Renal-Electrolyte Division, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Xingyu Zhang
- Department of Surgery, Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Amit Tevar
- Department of Surgery, Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Rajil Mehta
- Department of Medicine, Renal-Electrolyte Division, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Vikraman Gunabushanam
- Department of Surgery, Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Puneet Sood
- Department of Medicine, Renal-Electrolyte Division, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - William Hoffman
- Transplant Nephrology, UPMC Pinnacle, Harrisburg, Pennsylvania
| | - Sumit Mohan
- Department of Medicine, Division of Nephrology, Vagelos College of Physicians and Surgeons and Department of Medicine, Mailman School of Public Health, Columbia University, New York, New York
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Liwski R, Stepkowski S. The prospect for the diagnostic management team to streamline virtual and physical crossmatching. Transpl Immunol 2022; 73:101628. [DOI: 10.1016/j.trim.2022.101628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 05/17/2022] [Indexed: 11/28/2022]
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Wade J, Roback JD, Krummey SM, Gebel HM, Bray RA, Sullivan HC. Implementing virtual crossmatch based diagnostic management teams in human leukocyte antigen laboratories and transplant programs. Transpl Immunol 2022; 73:101629. [DOI: 10.1016/j.trim.2022.101629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 05/10/2022] [Accepted: 05/17/2022] [Indexed: 11/25/2022]
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Olszowska-Zaremba N, Zagożdżon R, Gozdowska J. Accuracy of virtual crossmatch (VXM) prediction of physical crossmatch (PXM) results of donor specific antibody (DSA) in routine pretransplant settings–A single-center experience. Transpl Immunol 2022; 72:101583. [DOI: 10.1016/j.trim.2022.101583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 03/15/2022] [Accepted: 03/15/2022] [Indexed: 11/26/2022]
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Principles of Virtual Crossmatch Testing for Kidney Transplantation. Kidney Int Rep 2022; 7:1179-1188. [PMID: 35685330 PMCID: PMC9171621 DOI: 10.1016/j.ekir.2022.03.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 02/14/2022] [Accepted: 03/07/2022] [Indexed: 11/21/2022] Open
Abstract
Human leukocyte antigens (HLAs) are the primary determinants of alloimmunity. A crossmatch test is a test that determines the immunologic risk of a recipient with a potential donor by ensuring that there are no transplant-relevant circulating antibodies in the recipient directed against donor antigens. Physical crossmatch (PXM) tests, such as complement-dependent cytotoxicity crossmatch (CDCXM) and flow cytometry crossmatch (FCXM), require mixing of patient serum and donor cells, are labor intensive, and are logistically challenging. Virtual crossmatch (VXM) test assesses immunologic compatibility between recipient and potential donor by analyzing the results of 2 independently done physical laboratory tests—patient anti-HLA antibody and donor HLA typing. The goal of VXM is pretransplant risk stratification—though there is no consensus on whether such risk assessment involves predicting the PXM result or the posttransplant outcome. Although the concept of VXM is not new, the advent of solid-phase assays for detecting circulating antibodies in the recipient directed against individual HLA and DNA-based methods for typing donor HLA specificities at a higher resolution makes the routine use of VXM a reality. Accordingly, VXM may be applied at different scenarios—both for sensitized and nonsensitized patients. Implementation of VXM-based approach has resulted in statistically significant reduction in cold ischemia time without an increase in hyperacute rejection episodes. Though there are considerable challenges, VXM is expected to be used more often in the future, depending on the transplant center’s tolerance of immunologic risk.
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