Measuring human leukocyte antigen alloantibodies: beyond a binary decision

Maguire, Chelsea H.; Schinstock, Carrie A.; Tambur, Anat R.

doi:10.1097/mot.0000000000000822

Cited by 4 publications

(6 citation statements)

References 31 publications

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“…There is a maximum number of antigens on these beads. Bead saturation and interference can occur leading to inaccurate results particularly among patients with a high quantity of HLA antibody ( 38 , 39 ). Performing these solid phase assays with diluted serum to determine antibody titer can provide a better quantitative assessment Figure 1 .…”

Section: Considerations For Outcome Assessmentmentioning

confidence: 99%

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Challenges and opportunities for designing clinical trials for antibody mediated rejection

Balakrishnan,

Alexander,

Schinstock

2024

Front. Transplant.

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Significant progress has been made in kidney transplantation, with 1-year graft survival nearing 95%. However, long-term allograft survival remains suboptimal, with a 10-year overall graft survival rate of only 53.6% for deceased donor transplant recipients. Chronic active antibody-mediated rejection (ABMR) is a leading cause of death-censored graft loss, yet no therapy has demonstrated efficacy in large, randomized trials, despite substantial investment from pharmaceutical companies. Several clinical trials aimed to treat chronic ABMR in the past decade have yielded disappointing results or were prematurely terminated, attributed to factors including incomplete understanding of disease mechanisms, heterogeneous patient populations with comorbidities, slow disease progression, and limited patient numbers. This review aims to discuss opportunities for improving retrospective and prospective studies of ABMR, focusing on addressing heterogeneity, outcome measurement, and strategies to enhance patient enrollment to inform study design, data collection, and reporting.

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Section: Considerations For Outcome Assessmentmentioning

confidence: 99%

“…As shown in these violin plots, the quantity of donor specific antibody can be vastly different (different titer) despite the same MFI. This emphasizes the point that MFI is not a reliable endpoint for DSA quantification in treatment trials(38). Reprinted with permission from Maguire CH, Schinstock CA, Tambur AR.…”

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confidence: 99%

Challenges and opportunities for designing clinical trials for antibody mediated rejection

Balakrishnan,

Alexander,

Schinstock

2024

Front. Transplant.

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“…For all titration experiments performed by Luminex, we utilized HLA-coated single antigen beads (SAB) from ThermoFisher/OneLamda (West Hills/CA/USA). 40 To circumvent the 'shared-epitope-phenomenon', 41,42 we used individual bead sets (SAB mono ), representing a single HLA type only. For each SAB titr -assay, we additionally used negative (uncoated) control beads (NCB).…”

Section: Single Hla Beadsmentioning

confidence: 99%

HLA antibody affinity determination: From HLA‐specific monoclonal antibodies to donor HLA specific antibodies (DSA) in patient serum

Hug,

Keller,

Marty

et al. 2023

HLA

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Organs transplanted across donor‐specific HLA antibodies (DSA) are associated with a variety of clinical outcomes, including a high risk of acute kidney graft rejection. Unfortunately, the currently available assays to determine DSA characteristics are insufficient to clearly discriminate between potentially harmless and harmful DSA. To further explore the hazard potential of DSA, their concentration and binding strength to their natural target, using soluble HLA, may be informative. There are currently a number of biophysical technologies available that allow the assessment of antibody binding strength. However, these methods require prior knowledge of antibody concentrations. Our objective within this study was to develop a novel approach that combines the determination of DSA‐affinity as well as DSA‐concentration for patient sample evaluation within one assay. We initially tested the reproducibility of previously reported affinities of human HLA‐specific monoclonal antibodies and assessed the technology‐specific precision of the obtained results on multiple platforms, including surface plasmon resonance (SPR), bio‐layer interferometry (BLI), Luminex (single antigen beads; SAB), and flow‐induced dispersion analysis (FIDA). While the first three (solid‐phase) technologies revealed comparable high binding‐strengths, suggesting measurement of avidity, the latter (in‐solution) approach revealed slightly lower binding‐strengths, presumably indicating measurement of affinity. We believe that our newly developed in‐solution FIDA‐assay is particularly suitable to provide useful clinical information by not just measuring DSA‐affinities in patient serum samples but simultaneously delivering a particular DSA‐concentration. Here, we investigated DSA from 20 pre‐transplant patients, all of whom showed negative CDC‐crossmatch results with donor cells and SAB signals ranging between 571 and 14899 mean fluorescence intensity (MFI). DSA‐concentrations were found in the range between 11.2 and 1223 nM (median 81.1 nM), and their measured affinities fall between 0.055 and 24.7 nM (median 5.34 nM; 449‐fold difference). In 13 of 20 sera (65%), DSA accounted for more than 0.1% of total serum antibodies, and 4/20 sera (20%) revealed a proportion of DSA even higher than 1%. To conclude, this study strengthens the presumption that pre‐transplant patient DSA consists of various concentrations and different net affinities. Validation of these results in a larger patient cohort with clinical outcomes will be essential in a further step to assess the clinical relevance of DSA‐concentration and DSA‐affinity.

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“…We have shown that despite having the same cPRA (99.9% at baseline) on undiluted serum sample, our cohort exhibited significant heterogeneity with regards to HLA antibody strength. Thus, the major advantage of combining cPRA calculation with serum dilution is the ability to incorporate two different metrics of sensitization (1) the breadth of sensitization and (2) the quantity of antibodies 21 . This key information can be used to identify patients presumed to be most likely to respond to desensitization at baseline (e.g., identify patients to include in desensitization trials) and the reduction in cPRA per dilution could be used as an endpoint to compare the efficacy of various therapies.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, the major advantage of combining cPRA calculation with serum dilution is the ability to incorporate two different metrics of sensitization (1) the breadth of sensitization and (2) the quantity of antibodies. 21 This key information can be used to identify patients presumed to be most likely to respond to desensitization at baseline (e.g., identify patients to include in desensitization trials) and the reduction in cPRA per dilution could be used as an endpoint to compare the efficacy of various therapies. An additional advantage of this measure is that it is sensitive enough to identify therapeutic efficacy that may not have been apparent with other endpoints.…”

Section: Introductionmentioning

confidence: 99%

Clinical utility of serial serum dilutions for HLA antibody interpretation

Tambur

Schinstock

2022

HLA

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Luminex single antigen bead (SAB) testing has increased the sensitivity and specificity of accurately identifying HLA antibodies, in support of all organ transplantation. However, as described in manufacturers' recommendation, the output of the assay, using mean fluorescence intensity (MFI) units, is only semi‐quantitative. Therefore, the ability to use MFI values to compare between different assays, to accurately guide clinical practice, or be used as an endpoint measure in clinical trials, is limited. To improve potential quantification, one must circumvent inherent limitations of SAB assays such as interference and saturation phenomena. In this review, we discuss how measurement of pre‐transplant serum dilutions can be used to determine unacceptable antigens for wait‐listing, determine the likelihood for successful HLA antibody reduction with desensitization, and compare degree of HLA (in)compatibility among various living donors. We also discuss how serum dilutions are optimal for measuring and comparing the efficacy of antibody depletion therapies for desensitization or antibody mediated rejection treatment post‐transplant. Historically, one of the main criticisms for the use of serum dilutions and titer has been the potential labor and cost associated with additional testing. Here, we show how only one or two dilutions can add major value in most circumstances. In summary, the practical use of serum dilutions and titer determination are important methods that can be used before and after transplantation of all organs to quantify antibody accurately and reliably in routine practice and in clinical trials.

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Measuring human leukocyte antigen alloantibodies: beyond a binary decision

Cited by 4 publications

References 31 publications

Challenges and opportunities for designing clinical trials for antibody mediated rejection

Challenges and opportunities for designing clinical trials for antibody mediated rejection

HLA antibody affinity determination: From HLA‐specific monoclonal antibodies to donor HLA specific antibodies (DSA) in patient serum

Clinical utility of serial serum dilutions for HLA antibody interpretation

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