Comparative performance evaluation of a donor-specific bead-based crossmatch technique for the detection of donor-specific anti-HLA antibodies in heart transplantation.

INTRODUCTION: Recently new human leukocyte antigen (HLA) antibody screening methods have been shown to significantly improve thoracic transplantation outcomes. The best combination of assays for both allocation and monitoring is still under investigation. Herein, we evaluated the correlation and clinical relevance of three methodologies to detect donor-specific anti-HLA antibodies (DSA).
METHODS: For the same donor-recipient combinations we compared the results of the Luminex donor-specific crossmatch (DSA-LX), using donor-isolated HLA antigens coated onto microbeads, with those of a flow-cytometric crossmatch (FCXM) and of the Luminex single-antigen bead methodology (SA-LX), wherein recombinant HLA molecules are coated onto microbeads. We compared 46 pre- (n = 27) and post-transplant (n = 19) serum samples using DSA-LX and SA-LX, while 27 pretransplant samples were additionally analyzed by FCXM.
RESULTS: Among the pretransplant sera, the 3 methods were in agreement for class I DSA in 22/27 (81.5%) samples and for class II DSA in 17/27 (63.0%) of tested samples. When the results of the 2 bead-based methodologies were compared with the FCXM methodology, the SA-LX results better correlated than the DSA-LX results both for class I and class II antibodies. Furthermore, the SA-LX results showed greater clinical relevance. The reproducibility scores for both the SA-LX and FCXM were 100%, whereas for the DSA-LX it was 85.5%.
CONCLUSIONS: DSA-LX did not correlate with FCXM and SA-LX to detect DSA, particularly for class II antibodies. Furthermore, in comparison to FCXM and SA-LX, DSA-LX showed lower reproducibility rendering the method not eligible for prediction, allocation, or monitoring purposes.