Eliminating False Positive Virtual Crossmatch Results for Lung Transplant Candidates by Using Multiple Antibody Testing Platforms.
1Department of Pathology and Laboratory of Medicine, Temple University, Lewis Katz School of Medicine, Philadelphia, PA
2Department of Cardiovascular Surgery, Temple University, Lewis Katz School of Medicine, Philadelphia, PA
Meeting: 2017 American Transplant Congress
Abstract number: B245
Keywords: Cadaveric organs, Histocompatibility, HLA antibodies, Lung transplantation
Session Information
Session Name: Poster Session B: Lung Transplantation Poster Session
Session Type: Poster Session
Date: Sunday, April 30, 2017
Session Time: 6:00pm-7:00pm
Presentation Time: 6:00pm-7:00pm
Location: Hall D1
Purpose: At present, immunologic risk for lung transplant patients is evaluated based on Virtual crossmatch (VXM) by comparing recipient's HLA antibodies detected by Single antigen bead (SAB) panels to prospective donor HLA antigens. Thorough antibody characterization is essential for accurate VXM to achieve a safe transplantation without a prospective cell-based crossmatch. To identify potential pitfalls in HLA antibody assignment, we have examined concordance between VXM and Retrospective Flow Cytometry Crossmatch (FCXM) results for 100 consecutive lung transplants.
Methods and Materials: Initial HLA antibody testing was performed using Luminex SAB assays. FCXM was done using 3-color analysis on a 1024 channel scale. Additional characterization of HLA antibody was performed using screening (FlowPRA and LSM) and specificity (LSPRA) assays.
Results: HLA antibody were detected in 49% of transplant recipients (13% patients had CPRA of 20-80% and 36% patients had CPRA of <20%). The concordance rate between VXM and FCXM results was 89%. Of 87 Negative VXM only one was false positive by FCXM. However, of 13 VXM predicted to result in positive FCXM due to the presence of DSAs, only 3 were positive, while 10 were negative (Figure 1). Using HLA antibody screening and specificity assays, we found that the 10% false positive VXM rate was observed due to antibodies against denatured HLA determinants on the SAB, which are not clinically relevant. Comprehensive antibody analysis of waitlist lung transplant candidates showed that 26% patients positive by SAB have antibody against denatured antigens.
Conclusion: Interpretation of HLA antibody profile based on multiple antibody testing platforms, rather than entirely on SAB assay, drastically improves the accuracy of VXM and prevents unnecessary exclusion of organ donors and/or inappropriate use of immunosuppressive therapy. 
CITATION INFORMATION: Timofeeva O, Kashem M, Geier S, Grogan D, Keshavamurthy S, Gomez-Abraham J, Toyoda Y, Cordova F. Eliminating False Positive Virtual Crossmatch Results for Lung Transplant Candidates by Using Multiple Antibody Testing Platforms. Am J Transplant. 2017;17 (suppl 3).
To cite this abstract in AMA style:
Timofeeva O, Kashem M, Geier S, Grogan D, Keshavamurthy S, Gomez-Abraham J, Toyoda Y, Cordova F. Eliminating False Positive Virtual Crossmatch Results for Lung Transplant Candidates by Using Multiple Antibody Testing Platforms. [abstract]. Am J Transplant. 2017; 17 (suppl 3). https://atcmeetingabstracts.com/abstract/eliminating-false-positive-virtual-crossmatch-results-for-lung-transplant-candidates-by-using-multiple-antibody-testing-platforms/. Accessed May 9, 2025.« Back to 2017 American Transplant Congress