P102 Prevalence of anti HLA antibodies in adult hematopoietic stem cell transplant recipients

Aim Recent studies have indicated that the presence of HLA donor specific antibodies (DSA) in patients undergoing mismatched hematopoietic stem cell transplantation (HSCT) represent a considerable risk factor for graft failure. Therefore, the role of pre-existing anti-HLA antibodies in HSCT has drawn increasing attention due to increased number of patients who receive partially HLA mismatched, HLA haploidentical and cord blood HSCT. The aim of this study is to determine the frequency of the presence of anti-HLA antibodies in our adult HSCT program. Method The presence of anti-HLA antibodies before transplantation was determined prospectively in 200 HSCT adult recipients at King Faisal Specialist Hospital and Research Center, using mixed screen beads in a solid phase assay Results Anti-HLA antibodies were detected in 127/200 of the patients (63%). Among those sensitized, 34/127 (27%) were sensitized to HLA class I only and 13/127 (10%) sensitized to HLA class II only and 80/127 (63%) sensitized to both HLA class I and HLA class II. Conclusion Our result has shown a higher level of HLA sensitization (64%) compared to several published studies that reported up to 40% HLA sensitization. Since our patient pool shows a higher prevalence of HLA sensitization, this further emphasizes the need to accurately identify the presence or absence of DSA; which if present poses a significant risk of delayed or complete graft failure.