Evaluation of rapid optimized flow cytometry crossmatch (Halifaster) in living donor kidney transplantation

Abstract

Kidney transplantation is often the preferred treatment for end‐stage renal disease. However, the presence of preformed donor‐specific antibodies (DSA), including those against HLA, can lead to antibody‐mediated rejection and significantly impact transplant outcomes. The Flow Cytometry Crossmatch (FCXM) is a crucial tool in kidney transplantation, as it also enables the measurement of low levels of anti‐HLA DSA antibodies. However, current methodologies for detecting these antibodies, however, are time‐consuming and require extensive reagents. In this study, we analyzed the performance of the Halifaster FCXM protocol in 133 consecutive living kidney donor pairs, correlating these results with single antigen‐based anti‐HLA DSA results. Anti‐HLA DSA was identified in 31 patients (23.3%). Both T and B lymphocyte FCXM assays demonstrated high sensitivity and specificity in detecting anti‐HLA DSA. Furthermore, a Tree model to determine the levels of anti‐HLA DSA to produce a flow crossmatch positivity, was developed offering an accuracy of 93% and 90% for T and B lymphocytes, respectively. Both approaches point to a thresh old of 1000–2000 MFI for T lymphocytes and 3000 MFI for B lymphocytes. Our findings indicate that the Halifaster protocol facilitates fast and efficient FCXM testing without compromising accuracy, marking a significant advancement in the field of kidney transplantation. The inclusion of HLA‐specific antibody analysis underscores the protocol's comprehensive approach to improving transplant outcomes.