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CONTEXT.: The blood bank is often consulted for transfusion support of patients with suspected platelet transfusion refractoriness (PTR). The workup is complex because testing includes specialized assays that are uncommonly ordered with limited availability. Add to this the variety of possible products-crossmatched platelets, human leukocyte antigen (HLA)-matched platelets, HLA antigen-negative platelets-and the approach to PTR can be overwhelming. Moreover, most literature on the subject is published in transfusion medicine journals aimed at transfusion medicine physicians and blood bank specialists in academic settings. Resources tailored to community hospital blood banks are lacking. OBJECTIVE.: To provide pathologists who may not have subspecialized training in transfusion medicine and who direct blood banks algorithmic workflows based on clinical scenario and test availability to provide appropriate transfusion support for patients with PTR. DATA SOURCES.: This review is a comprehensive overview of terminology, HLA testing procedures, interpretations, and practical recommendations for managing PTR in various scenarios based on expert opinion as well as relevant medical literature published from 2007 to 2022. CONCLUSIONS.: Consultation on PTR is complicated and encompasses many clinical and laboratory aspects. The lack of guidelines derived from high-quality prospective studies poses challenges in the workup and management of PTR. Hindering the process further are limited test availability, unfamiliarity with the technical assays, and the various specialized platelet products. The clinical evaluation algorithm presented herein along with the workflow pathways offer pathologists user-friendly and best-practice guidelines with different options based on the clinical scenario and the tests available.
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Background: Biomarkers that predict posttransplant alloimmunity could lead to improved long-term graft survival. Evaluation of the number of mismatched epitopes between donor and recipient HLA proteins, termed molecular mismatch analysis, has emerged as an approach to classify transplant recipients as having high, intermediate, or low risk of graft rejection. When high-resolution genotypes are unavailable, molecular mismatch analysis requires algorithmic assignment, or imputation, of a high-resolution genotyping. Although imputation introduces inaccuracies in molecular mismatch analyses, it is unclear whether these inaccuracies would impact the clinical risk assessment for graft rejection. Methods: Using renal transplant patients and donors from our center, we constructed cohorts of surrogate donor-recipient pairs with high-resolution and low-resolution HLA genotyping that were racially concordant or discordant. We systemically assessed the impact of imputation on molecular mismatch analysis for cohorts of 180-200 donor-recipient pairs for each of 4 major racial groups. We also evaluated the effect of imputation for a racially diverse validation cohort of 35 real-world renal transplant pairs. Results: In the surrogate donor-recipient cohorts, imputation preserved the molecular mismatch risk category for 90.5%-99.6% of racially concordant donor-recipient pairs and 92.5%-100% of racially discordant pairs. In the validation cohort, which comprised 72% racially discordant pairs, we found that imputation preserved the molecular mismatch risk category for 97.1% of pairs. Conclusions: Overall, these data demonstrate that imputation preserves the molecular mismatch risk assessment in the vast majority of cases and provides evidence supporting imputation in the performance of molecular mismatch analysis for clinical assessment.
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OBJECTIVES: To determine whether the information provided by short tandem repeat (STR) testing and bone marrow (BM) biopsy specimens following hematopoietic stem cell transplant (HSCT) provides redundant information, leading to test overutilization, without additional clinical benefit. METHODS: Cases with synchronous STR and flow cytometric immunophenotyping (FCI) testing, as part of the BM evaluation, were assessed for STR/FCI concordance. RESULTS: Of 1199 cases (410 patients), we found the overall concordance between STR and FCI was 93%, with most cases (1063) classified as STR-/FCI-. Of all discordant cases, 75 (6%) were STR+/FCI-, with only 5 (6.7%) cases best explained as identification of disease relapse. Eight cases were STR-/FCI+, representing relapsed/residual disease. Analysis of cases 1 year or more from transplant (54% of all cases) indicated only 9 (1.5%) were STR+/FCI-, and none uniquely identified relapse. CONCLUSIONS: These data suggest that STR analysis performed 1 year or more post-HSCT does not identify unknown cases of relapse. Furthermore, while STR testing is critical for identifying graft failure/rejection within the first year posttransplant, FCI appears superior to STR at detecting late relapses with low-level disease. Therefore, STR testing from patients 1 year or more post-HSCT may be unnecessary, as BM biopsy evaluation is sufficient to identify disease relapse.
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BACKGROUND: Increasing indications for cellular therapy collections have stressed our healthcare system, with autologous collections having a longer than desired wait time until apheresis collection. This quality improvement initiative was undertaken to accommodate more patients within existing resources. STUDY DESIGN AND METHODS: Patients with multiple myeloma who underwent autologous peripheral blood stem cell collection from October 2022 to April 2023 were included. Demographic, mobilization, laboratory, and apheresis data were retrospectively collected from the medical record. RESULTS: This cohort included 120 patients (49.2% male), with a median age of 60 years. All received G-CSF and 95% received pre-emptive Plerixafor approximately 18 hours pre-collection. Most (79%) had collection goals of at least 8 × 106/kg CD34 cells, with 63% over 70 years old having this high collection goal (despite 20 years of institutional data showing <1% over 70 years old have a second transplant). With collection efficiencies of 55.9%, 44% of patients achieved their collection goal in a single day apheresis collection. A platelet count <150 × 103/µL on the day of collection was a predictor for poor mobilization; among 27 patients with a low baseline platelet count, 17 did not achieve the collection goal and 2 failed to collect a transplantable dose. CONCLUSIONS: With minor collection goal adjustments, 15% of all collection appointments could have been avoided over this 6-month period. Other strategies to accommodate more patients include mobilization modifications (Plerixafor timing or substituting a longer acting drug), utilizing platelet counts to predict mobilization, and modifying apheresis collection volumes or schedule templates.
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Bencilaminas , Ciclamas , Factor Estimulante de Colonias de Granulocitos , Movilización de Célula Madre Hematopoyética , Mieloma Múltiple , Trasplante Autólogo , Humanos , Mieloma Múltiple/terapia , Ciclamas/farmacología , Ciclamas/uso terapéutico , Persona de Mediana Edad , Masculino , Femenino , Factor Estimulante de Colonias de Granulocitos/administración & dosificación , Movilización de Célula Madre Hematopoyética/métodos , Anciano , Estudios Retrospectivos , Eliminación de Componentes Sanguíneos/métodos , Compuestos Heterocíclicos/administración & dosificación , Compuestos Heterocíclicos/uso terapéutico , Adulto , Trasplante de Células Madre de Sangre Periférica/métodos , Recuento de PlaquetasRESUMEN
BACKGROUND: Platelet-transfusion refractory (PR) patients do not achieve expected post-transfusion platelet counts. We investigate suspected PR patients with post-transfusion platelet counts, indirect platelet antibody screens (ind-PAS), Class I HLA antibody tests (HLA-Scr), and physical platelet crossmatch (PXM) studies. STUDY DESIGN AND METHODS: The three following cases describe possible pitfalls of laboratory tests used in PR workup and management. RESULTS: Case #1: Antibody testing detected antibodies to only HLA-B13, corresponding to a 4% calculated panel reactive antibodies (CPRA; 96% predicted donor compatibility). However, PXM showed the patient compatible with 11/14 (79%) donors; two of the PXM-incompatible units were ABO-incompatible. Case #2: PXM revealed compatibility with 1/14 screened donors; however, the patient did not respond to the product from the compatible donor. The patient did respond to HLA-matched product. Dilution studies provided evidence of the prozone effect, which caused negative PXM despite clinically relevant antibodies. Case #3: There was a discrepancy between the ind-PAS and HLA-Scr. Ind-PAS was negative for HLA antibodies, while HLA-Scr was positive and specificity testing corresponded to 38% CPRA. Per the package insert, the sensitivity of ind-PAS is ~85% compared to HLA-Scr. DISCUSSION: These cases highlight the importance of investigating incongruent results. Cases #1 and #2 demonstrate PXM pitfalls: ABO incompatibility can result in positive PXM and false-negative PXM can occur in the setting of the prozone effect. Case #3 reveals the importance of knowing a test's sensitivity. Centers that only perform ind-PAS may fail to detect HLA antibodies.
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Tipificación y Pruebas Cruzadas Sanguíneas , Plaquetas , Transfusión de Plaquetas , Humanos , Anticuerpos , Prueba de Histocompatibilidad , Antígenos HLA , Recuento de Plaquetas , Transfusión de Plaquetas/métodosRESUMEN
Short tandem repeat (STR) analysis to assess chimerism is a critical aspect of routine care particularly in patients facing stem cell transplants but is also relevant in other clinical scenarios. STR analysis provides a means to assess donor and recipient cellular origins in a patient, and, as such, can inform engraftment, rejection, and relapse status in stem cell transplant recipients. In this review of STR testing, the most commonly used method to assess chimerism, its background, procedural details, and clinical utility are discussed.
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Trasplante de Células Madre Hematopoyéticas , Humanos , Quimerismo , Trasplante de Células Madre , Donantes de Tejidos , RecurrenciaRESUMEN
The Histocompatibility and Identity Testing Committee offers an overview of the College of American Pathologists' (CAP) Proficiency Testing (PT) program, commemorating its significant 75th anniversary in 2024. The CAP PT program has undergone significant growth and evolution over the years, ultimately achieving Centers for Medicare and Medicaid Services approval. In 1979, CAP's partnership with the American Association for Clinical Histocompatibility Testing marked a pivotal moment, leading to the creation of the first proficiency testing survey in 1980. This laid the foundation for various PT programs managed by the CAP Histocompatibility and Identity Testing Committee, including HLA antibody testing, HLA molecular typing, engraftment monitoring, parentage/relationship testing, HLA disease associations and drug risk, and HLA-B27 typing. Each program's distinctive considerations, grading methodologies, and future prospects are detailed here, highlighting the continual evolution of histocompatibility and identity testing PT to support emerging technologies and evolving laboratory practices in the field.
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Trasplante de Riñón , Supervivencia de Injerto , Humanos , Riñón , Donadores Vivos , Estudios Prospectivos , Donantes de TejidosRESUMEN
BACKGROUND: Tn syndrome is an acquired form of polyagglutination arising from somatic mutations of hematopoietic stem cells. Tn red blood cells (RBCs) are agglutinable by naturally occurring anti-Tn antibodies in most adult sera. Current ABO typing reagents are monoclonal and do not detect polyagglutination on forward typing. However, herein we describe a case of Tn activation that was suspected due to cross-reactivity with a monoclonal anti-A reagent. STUDY DESIGN AND METHODS: A 63-year-old man with myeloproliferative neoplasm, who historically typed as group O, demonstrated unexpected mixed field reactivity with anti-A reagent using a gel-based method. However, manual tube testing was consistent with the patient's historical group O type. RESULTS: Lectin testing demonstrated reactivity with Salvia sclarea and Glycine soja, but not Arachis hypogea. The patient's RBCs produced positive crossmatches with healthy donor sera, but reactivity was eliminated by ficin pretreatment of the RBCs. Ficin treatment also resolved typing discrepancies on gel-based typing. No reactivity was noted using cord blood sera, and N antigen expression was diminished upon phenotyping. Tn activation was confirmed by detection of a novel 4-nucleotide deletion (c.395-398del) in exon 3 of C1GALT1C1 resulting in a truncated glycosyltransferase. CONCLUSION: This case of acquired Tn polyagglutination due to a novel mutation was first suspected from an ABO phenotyping discrepancy. It highlights the cross-reactivity of anti-A reagent with Tn antigen when tested on a common gel-based method. Furthermore, the case demonstrates that review of patient history and test information can clarify discrepancies and guide resolution.
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Sistema del Grupo Sanguíneo ABO , Ficaína , Adulto , Antígenos de Carbohidratos Asociados a Tumores , Tipificación y Pruebas Cruzadas Sanguíneas , Humanos , Masculino , Persona de Mediana EdadRESUMEN
Histocompatibility testing has continuously evolved since its inception. One such advancement is the implementation of the virtual crossmatch (VXM). Recent changes to allograft allocation schemes have resulted in increased organ sharing over greater distances, resulting in expanded utilization of the VXM to assess donor: recipient compatibility. In fact, the VXM has become a major arbitrator of pre-transplant compatibility assessment prior to both deceased and living donor organ allocation. This shift in pre-transplant practice is concurrent with the US healthcare systems' move towards more inclusive and coordinated team-based management approach to disease diagnosis. Diagnostic Management Teams (DMTs) exemplify this shift in patient care. Our institution seized the opportunity to build and implement a VXM DMT to improve and streamline pre-transplant assessment. This VXM DMT is compliant with US regulatory standards and provides a consultative report containing relevant pre-transplant information, test interpretation as well as recommendations for HLA additional (if any) testing. Herein we describe the development of and experience with the VXM DMT a year after its launch.
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Antígenos HLA , Laboratorios , Tipificación y Pruebas Cruzadas Sanguíneas , Antígenos de Histocompatibilidad Clase I , Antígenos de Histocompatibilidad Clase II , Prueba de Histocompatibilidad/métodos , Humanos , Isoanticuerpos , Donadores VivosRESUMEN
HLA genotyping has undergone a rapid progression in resolution since the development of DNA-based typing methods. Despite the advent of high-resolution next-generation sequencing, the bulk of solid organ genotyping is performed at intermediate resolution, which provides multiple possible two-field results for each classical HLA loci. As a result, several methodologies have been developed to impute the most likely allele-level (two-field) HLA genotype for the purposes of donor-recipient compatibility analysis. The advent of molecular mismatch analysis, however, has placed a new emphasis on the accuracy of imputation. While seminal molecular mismatch studies have relied on the imputation of intermediate resolution genotyping, several recent studies have performed analysis showing that imputation generates inaccuracies in epitope identification. While the clinical impact of these errors is not clear, it is important that these concerns do not preclude future progress in understanding the utility of molecular mismatch analysis in transplantation. In the future, advances in genotyping methods will result in routine two-field resolution that will abrogate these concerns. In the meantime, however, studies are needed in order to address the role of molecular mismatch in diverse patient populations and to carefully address the potential of molecular mismatch analysis in the context of imputation.
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Antígenos HLA , Trasplante de Órganos , Alelos , Genotipo , Antígenos HLA/genética , Prueba de Histocompatibilidad/métodos , Humanos , Donantes de TejidosRESUMEN
Background and Objectives: Immune checkpoint inhibitors (ICIs) have less toxicity than standard chemotherapy and are now standard of care for many patients with advanced cancer. A manageable side effect profile and potential for durable responses may lead to aggressive care of the palliative patient. We sought to evaluate palliative care input and ICI use at the end of life at two Irish cancer centres. Methods: We identified deceased patients who received at least one dose of an ICI between first of January 2013 to 31st of December 2018. A retrospective electronic chart review was performed. Results: The electronic records of 102 patients were analysed. Fifty eight percent were male and the median age of diagnosis of advanced disease was 60 years (range 17-78). Median time from last dose of ICI to death was 57 days (range 8-574) and 20% of patients died within 30 days of last dose of ICI. Most patients, 92%, were referred to palliative care. The median time from palliative care referral to death was 64 days (range 1- 1010). In the last 30 days of life, 39% of patients attended the emergency department (ED) and 46% had at least one hospital admission. Late palliative care referrals, ≤3 months before death, were associated with hospitalisations in the last month of life (64% vs. 36%, P = .02). Timing of palliative care referral did not affect ICI prescribing at the end of life (P = 0.38). ICI use in the last 30 days of life was not associated with increased ED presentations or hospitalisations at the end of life. Patients who received ICI in the last month had a higher likelihood of in-hospital death (43% vs. 16%, P = 0.02). Conclusions: ICI within 30 days of death was associated with dying in hospital but did not lead to more hospitalisations and emergency department presentations. Early palliative care did not affect ICI use but reduced hospitalisations at the end of life.
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Eplet mismatch load, both overall and at the single molecule level, correlates with transplant recipient outcomes. However, precise eplet assessment requires high-resolution HLA typing of both the donor and recipient. Anything less than high-resolution typing requires imputation of HLA types. The currently available methods to identify eplet mismatch are both tedious and demanding. Therefore, we developed a software package and user-friendly web application (hlaR), that simplifies the workflow of eplet analysis, provides functions to impute high-resolution from low-resolution data and calculates both overall and single molecule eplet mismatch for single or multiple donor recipient pairs. Compared to manual assessments using currently available tools (namely, HLAMatchMaker), hlaR resulted in only minimal discrepancy in eplet mismatches (mean absolute difference of 0.56 for class I and 0.86 for class II for unique sum across loci). Additionally, output of the single molecule eplet function compared well to manual calculation, with an average single antigen count increase of 0.19. Importantly, the hlaR tool permits rapid and reproducible imputation and eplet mismatch including comparison between eplet reference tables (e.g. HLAMatchMaker version 2 or 3). Users can import data from a spreadsheet rather than relying on keystroke entry of individual donor and recipient data, thus reducing the risk of data entry errors. The resulting improved scalability of the hlaR tool is highlighted by plotting analysis time against the size of the input dataset. The new hlaR tool can provide eplet mismatch data with a streamlined workflow. With decreased effort from the end user, eplet matching and mismatch load data can be further incorporated into both research and clinical use.
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Rechazo de Injerto , Trasplante de Riñón , Antígenos HLA/genética , Prueba de Histocompatibilidad/métodos , Humanos , Donantes de Tejidos , Receptores de TrasplantesRESUMEN
BACKGROUND: Recent data suggests an association between blood hyperviscosity and both propensity for thrombosis and disease severity in patients with COVID-19. This raises the possibility that increased viscosity may contribute to endothelial damage and multiorgan failure in COVID-19, and that therapeutic plasma exchange (TPE) to decrease viscosity may improve patient outcomes. Here we sought to share our experience using TPE in the first 6 patients treated for COVID-19-associated hyperviscosity. STUDY DESIGN AND METHODS: Six critically ill COVID-19 patients with plasma viscosity levels ranging from 2.6 to 4.2 centipoise (cP; normal range, 1.4-1.8 cP) underwent daily TPE for 2-3 treatments. RESULTS: TPE decreased plasma viscosity in all six patients (Pre-TPE median 3.75 cP, range 2.6-4.2 cP; Post-TPE median 1.6 cP, range 1.5-1.9 cP). TPE also decreased fibrinogen levels in all five patients for whom results were available (Pre-TPE median 739 mg/dL, range 601-1188 mg/dL; Post-TPE median 359 mg/dL, range 235-461 mg/dL); D-dimer levels in all six patients (Pre-TPE median 5921 ng/mL, range 1134-60 000 ng/mL; Post-TPE median 4893 ng/mL, range 620-7518 ng/mL); and CRP levels in five of six patients (Pre-TPE median 292 mg/L, range 136-329 mg/L; Post-TPE median 84 mg/L, range 31-211 mg/L). While the two sickest patients died, significant improvement in clinical status was observed in four of six patients shortly after TPE. CONCLUSIONS: This series demonstrates the utility of TPE to rapidly correct increased blood viscosity in patients with COVID-19-associated hyperviscosity. Large randomized trials are needed to determine whether TPE may improve clinical outcomes for patients with COVID-19.
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Viscosidad Sanguínea , COVID-19 , Intercambio Plasmático , SARS-CoV-2/metabolismo , Adulto , Anciano , COVID-19/sangre , COVID-19/terapia , Humanos , Masculino , Persona de Mediana EdadAsunto(s)
Rechazo de Injerto/inmunología , Antígenos HLA/metabolismo , Prueba de Histocompatibilidad/métodos , Trasplante de Riñón , Alelos , Donación Directa de Tejido , Rechazo de Injerto/prevención & control , Antígenos HLA/genética , Humanos , Técnicas de Diagnóstico Molecular , Medición de Riesgo , Interfaz Usuario-ComputadorRESUMEN
In November 2014, the OPTN/UNOS Board of Directors mandated that HLA-DPB1 typing be performed for all deceased donors. Currently, there are over 1,000 known HLA DPB1 alleles, yet fewer than 30 are represented on commonly used single antigen bead (SAB) solid phase antibody assays. Moreover, the official World Health Organization (WHO) nomenclature for the DPB1 locus does not permit assessment of structural relationships between alleles based on their names. Thus, for donor DPB1 alleles lacking a corresponding SAB, determining the compatibility between a donor-recipient pair when the recipient possesses DPB1 antibodies currently requires the use of manual sequence alignments. Multiple studies have reported that DPB1 alleles can be classified into serological-defined categories based on shared protein sequence motifs residing in distinct hypervariable regions. To date, six such motifs have been recognized. To address this problem, we developed a computer-assisted tool to compare donor and recipient DPB1 allele sequences, specifically those defined by DPB1 hypervariable region motifs located in exon 2 (http://dpreport.hlatools.org). This tool quickly identifies mismatched DPB1 motifs, and easily permits the identification of motif-based donor-specific antibodies (DSA) to DPB1.
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Exones/genética , Cadenas beta de HLA-DP/genética , Polimorfismo Genético/genética , Alelos , Secuencia de Aminoácidos , Electrónica/métodos , Prueba de Histocompatibilidad/métodos , Humanos , Donantes de TejidosRESUMEN
As the world faces the current SARS-CoV-2 pandemic, extensive efforts have been applied to identify effective therapeutic agents. Convalescent plasma collected from recovered patients has been a therapeutic modality employed for over a hundred years for various infectious pathogens. Specifically, it has been used in the treatment of many viral infections with varying degrees of clinical efficacy. As we consider the use of convalescent plasma in the battle against this new strain of coronavirus, it is prudent to review what is known from past experiences. Accordingly, the aim of this review is to examine in detail studies of convalescent plasma used during previous viral outbreaks and pandemics with particular focus on hemorrhagic fevers, influenza, and other coronaviruses. The concluding sections of this review address the potential use of convalescent plasma during the present-day SARS-CoV-2 pandemic, not only insofar as its clinical benefit but also the steps required to make convalescent plasma treatments readily available for an exponentially growing patient population. By the end, the authors hope to address the extent to which convalescent plasma represents a realistic therapeutic approach, or a distraction from other potentially useful treatments.
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Infecciones por Coronavirus/terapia , Neumonía Viral/terapia , COVID-19 , Fiebre Hemorrágica Ebola/terapia , Humanos , Inmunización Pasiva , Inmunoglobulinas Intravenosas/uso terapéutico , Gripe Humana/terapia , Pandemias , Síndrome Respiratorio Agudo Grave/terapia , Resultado del Tratamiento , Sueroterapia para COVID-19RESUMEN
The virtual crossmatch (VXM) is gaining acceptance as an alternative approach to assess donor:recipient compatibility prior to transplantation. In contrast to a physical crossmatch, the virtual crossmatch does not require viable donor cells but rather relies on complete HLA typing of the donor and current antibody assessment of the recipient. Thus, the VXM can be performed in minutes which allows for faster transplant decisions thereby increasing the likelihood that organs can be shipped across significant distances yet safely transplanted. Here, we present a brief review of the past 50 years of histocompatibility testing; from the original complement-dependent cytotoxicity crossmatch in 1969 to the new era of molecular HLA typing, solid-phase antibody testing and virtual crossmatching. These advancements have shaped a paradigm shift in our approach to transplantation. That is, foregoing a prospective physical crossmatch in favor of a VXM. In this review, we undertake an in-depth analysis of the pros- and cons- of physical and virtual crossmatching.Finally, we provide objective data on the selected use of the VXM which demonstrate the value of a VXM in lieu of the traditional physical crossmatch for safe and efficient organ transplantation.