Kidney Week 2025 Annual Meeting-Navigating Human Leukocyte Antigens

Video Transcription

Video Summary

The session “Navigating the HLA Antigens” reviewed modern approaches to assessing immunologic compatibility and managing sensitized kidney transplant candidates. Elaine Reed presented virtual crossmatch (VXM) as connecting donor high‑resolution HLA typing with a recipient’s antibody profile from single‑antigen bead testing. She emphasized interpretive pitfalls: MFI values are semi‑quantitative, antigen expression differs by locus (e.g., lower C/DP expression), and labs often use locus‑specific positivity thresholds. Accurate VXM also depends on up‑to‑date sera and knowledge of sensitizing events; a case showed delayed post‑transfusion antibody development leading to an unexpectedly strong physical crossmatch. Programs therefore need center‑specific agreements with HLA labs on sampling frequency, unacceptable antigens, and when to require physical crossmatch.<br /><br />A desensitization update highlighted shifting goals—from converting a positive CDC crossmatch to broader aims such as reducing DSA and ABMR risk—and the need to integrate desensitization with other access strategies (kidney exchange, allocation programs). The key new therapy discussed was imlifidase, which rapidly cleaves IgG to enable transplantation across positive crossmatches (EMA conditional authorization). Real‑world experience shows clear access benefits but frequent antibody rebound and early ABMR, driving efforts to refine patient selection, post‑transplant immunomodulation, and precision monitoring (including deeper tissue phenotyping).<br /><br />Chris Wiebe discussed molecular/eplet mismatch as a biomarker for de novo DSA, rejection, and long‑term risk, showing how combining recipient age with class II molecular mismatch can guide personalized monitoring and immunosuppression decisions.<br /><br />Finally, Jenny Tran reviewed machine‑learning applications to predict flow crossmatch results, identify likely spurious bead reactivities, and discover immunogenic amino‑acid mismatch features, while underscoring the need for external validation, interpretability, and workflow integration.

Asset Subtitle

Moderator(s): Enver Akalin, Elaine Reed

Presentation(s):

Virtual Crossmatch in Kidney Transplantation: When and How? - Anat Tambu, Elaine Reed
Desensitization in Kidney Transplantation: What's New? - Carmen Lefaucheur
Use of Advanced HLA Epitope and Eplet Matching to Stratify Immunologic Risk - Chris Wiebe
Machine-Learning Approaches to HLA-Based Risk Stratification in Kidney Transplantation - Jenny Tran

Meta Tag

Date 11/6/2025

Pathway 1 Kidney Transplantation

Session ID 507649

Keywords

HLA antigens

virtual crossmatch (VXM)

high-resolution HLA typing

single-antigen bead assay

mean fluorescence intensity (MFI) thresholds

donor-specific antibodies (DSA)

sensitized kidney transplant candidates

desensitization strategies

imlifidase (IgG cleavage)

antibody-mediated rejection (ABMR)

molecular/eplet mismatch

machine learning crossmatch prediction