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

Luis Ramalhete, Rúben Araújo, Cristiana Teixeira, Ana Teixeira, Paula Almeida, Isabel Silva, Alice Lima

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish
Article numbere15391
Issue number2
Publication statusPublished - Feb 2024


  • donor specific antibodies
  • flow cytometry crossmatch
  • Halifaster protocol
  • kidney transplantation
  • living donor


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