Comparison of antibody monitoring system with flow cytometric crossmatch test in renal transplant recipients with high panel-reactive antibody

Background/Aims: The antibody monitoring system (AMS) is a recently developed enzyme-linked immunosorbent assay (ELISA) crossmatch assay to detect donor-specific anti-HLA immunoglobulin G antibodies (DS-HLA Abs). This study was conducted to compare the AMS with the flow cytometric crossmatch (FCXM) test in renal transplant recipients with high panel-reactive antibody (PRA). Methods: Thirty-two sera were obtained from 10 patients with panel reactivity above 50%. When anti-HLA Ab was detected by ELISA PRA and the matched donor had the corresponding HLA antigen, it was considered to indicate DS-HLA Ab. The results of the AMS assay and FCXM were compared with the DS-HLA Abs. Results: Twenty-three (71.9%) sera were positive for DS-HLA Abs by ELISA PRA. The AMS assay showed that the number of compatible sera with DS-HLA Abs was 27 (84.4%), and it was significantly concordant (κ = 0.649, p < 0.0001). For FCXM, the number of compatible sera with DS-HLA Abs was 26 (81.3%), and it was also significantly concordant (κ = 0.614, p < 0.0001). There was a significant degree of concordance between the AMS assay and FCXM in detection of DS-HLA Abs (κ = 0.452, p = 0.010). Conclusion: The AMS assay is comparable to FCXM in detecting DS-HLA Abs in high PRA recipients.