Date: Saturday, May 2, 2015
Session Name: Poster Session A: Kidney Antibody Mediated Rejection
Session Time: 5:30pm-7:30pm
Presentation Time: 5:30pm-7:30pm
Location: Exhibit Hall E
Background: Chronic allograft dysfunction remains the main obstacle for long-term success of kidney transplantation. Immunological factors, in particular HLA-antibodies, contribute to long-term allograft loss. Identification of de novo donor specific antibodies (dnDSA) by Luminex® technology is currently used for assessment of humoral rejection. Recently a C1q-Luminex® assay has been developed to identify complement binding HLA antibodies with highest sensitivity. Yet, clinical implication of dnDSA and C1q-fixing dnDSA detection remains unclear for medical practice, including protocol biopsy performance and therapeutic decisions. The main aims of this study were first, to improve the sensitivity of the C1q-Luminexò assay and second, to determine the clinical impact of C1q fixing dnDSA on kidney allograft outcome.
Methods: We selected stored serum samples of 10 kidney transplant recipients who developed dnDSA. Sera were tested for the dnDSA C1q fixing ability using a modified C1q-Luminex® Single Antigen Beads assay. To improve the C1q assay, we adjusted three steps of the protocol in 2 cross titration tests. Biological correlates of allograft function were assessed by serum creatinine and daily proteinuria.
Results: First, the protocol of C1q-Luminex® assay was modified: we were able to improve sensitivity with optimal dilution resulting in a 5-fold increase in MFI value. Six patients out of 10 had C1q-dnDSA. The median MFI of IgG-dnDSA were significantly higher in C1q positive patients (10991.5 vs 5235.5, respectively for C1q positive and C1q negative patients, p=0.0002). Five patients experienced rejection. Only 2/5 patients experienced antibody-mediated rejection: 1 pure ABMR, 1 mixed ABMR and TCMR. The first was positive and the second negative for C1q DSA. There was no correlation between C1q positivity with, neither serum creatinine nor daily proteinuria.
Conclusions: We clearly improved the sensitivity of the C1q-Luminex® assay. C1q positivity correlated with higher MFI in standard Luminex® assay. The clinical value of C1q positivity needs to be further investigated. Further clinical data with the modified assay are ongoing in a larger cohort.
To cite this abstract in AMA style:Roodenburg A, Bamoulid J, Staeck O, Schoenemann C, Lachmann N, Budde K. First Clinical Data With an Improved C1q-Luminex® Assay [abstract]. Am J Transplant. 2015; 15 (suppl 3). https://atcmeetingabstracts.com/abstract/first-clinical-data-with-an-improved-c1q-luminex-assay/. Accessed December 1, 2020.
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