Assessment of the LIFECODES LMX XP kits for HLA Antibody Screening in Potential Haematopoietic Stem Cell Transplant Recipients With HLA-DP Mismatch Donor

Abstract

National guidelines strongly recommend that patients being considered for HLA-mismatched stem cell transplant should be screened for HLA antibodies as the presence of donor specific antibodies can cause delayed engraftment. This project evaluated the use of LMX XP screening kit for antibody screening in patients with 10/10 but DPB1 mismatched unrelated donors.The Werfen LMX XP kits include an additional 2 beads that can detect HLA-DP antibodies. As the previous LMX deluxe kit did not include HLA-DP detection, a direct comparison between the 2 kits cannot be made. Instead, the LMX XP kits performance was evaluated against the Werfen Luminex Single Antigen (LSA) kit. 37 samples known to be positive for HLA-DP antibodies, as defined by LSA results with mean fluorescence intensity (MFI) values exceeding 1000, were analysed using all three assays. As expected, the LSA kit consistently demonstrated superior sensitivity and specificity in detecting HLA antibodies compared with the LMX XP kit. In particular, the LSA assay more reliably identified HLA-DP specificities, due to their single antigen bead design. In contrast, the LMX XP kit with their multi-antigen beads, while effective as a broad screening tool, showed reduced sensitivity for HLA-DP antibodies. Which was highlighted in the results, of the 37 samples that had DPB1 antibodies detected by single antigen only half were also detected by the LMX XP kit. The data showed there was an association between positive antibody detection with samples that had high MFI levels and high immunogenicity DP antigens. In conclusion, this project emphasises the strengths and limitations of both kits and supports the continued use of LSA for detailed antibody analysis and the LMX XP kit is not a replacement, particularly in the context of HLA-DP antibody detection in HSCT patients.