Late Breaking Abstract - B-Cell Crossmatch Positivity Predicts Worse CLAD-Free Survival Post-Lung Transplant

<bold>Introduction:</bold> Chronic lung allograft dysfunction (CLAD) is the main cause of long-term graft failure after lung transplantation (LuTx), with pre-sensitization to anti-HLA antibodies increasingly recognized as a contributing factor. This single-centre retrospective cohort study assessed the impact of pre-sensitization on CLAD-free survival. <bold>Methods:</bold> We included all patients transplanted between January 2020 and November 2024 with available anti-HLA antibody screening and crossmatch results at LuTx. Data were censored in November 2024. CLAD-free survival was analyzed using the log-rank test. <bold>Results:</bold> Of 322 eligible patients, 313 (97%) were included. Anti-HLA antibodies were found in 107 patients (34%): 23 (22%) had both class I and II, 39 (36%) class I only, and 45 (42%) class II only. A trend toward reduced CLAD-free survival was observed in patients with both class I and II antibodies (p = 0.09), but not in those with only one class or with any anti-HLA antibodies overall. A positive B-cell crossmatch (n = 40; 13%) was significantly associated with worse CLAD-free survival (p = 0.01; Figure). <fig><object-id>erj;66/suppl_69/PA5275/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig> <bold>Conclusion:</bold> Pre-sensitization with both class I and II antibodies may reduce CLAD-free survival, suggesting a synergistic effect. A positive B-cell crossmatch was significantly linked to worse outcomes, highlighting the importance of immunological risk assessment in optimizing long-term graft survival after LuTx.