Prevalence of HLA antibodies in female blood donors in Singapore

Abstract

Aim Antibodies against the human leukocyte antigen (HLA) in donors’ blood are implicated in the development of transfusion-related acute lung injury (TRALI). The majority of TRALI cases are caused by transfusion of plasma-rich components from female blood donors with HLA antibodies. In Singapore, female donors constitute about 32–34% of the total donor population. While HLA Class I and Class II antibody tests are widely available, the baseline prevalence of alloimmunized female donors has not been established. Methods The study was completed within a month long period to ensure no repeated donors. There were 6,519 whole blood and 545 apheresis donors and of which 2,210 (34%) and 18 (3%) were females respectively. A total of 315 female high risk blood donors were screened for HLA Class I and II (IgG) antibodies using flow cytometric panel reactive antibody method (Flow-PRA). Female donors were considered to be high risk if they have a history of transfusion, abortion, miscarriage or pregnancy. Results Among the 315 high risk female donors screened for HLA antibody, 105 donors (33.4%) demonstrated HLA sensitization. Of these 105, 58 (55.2%) were positive for Class I only, 33 (31.4%) were positive for Class II only and 14 (13.3%) were positive for both Class I and II antibodies. There were a total of 2228 female donors during the study period, of which 315 (14.1%) were found to be highly risked for alloimmunization. The percentage of sensitized female donors out of the total female donor population was 4.7%. Conclusions The overall prevalence of high-risk female donors is 14.1% and the prevalence of high-risk alloimmunized female donors is at 4.7%. The prevalence results from this study will help address whether reduction strategies involving the avoidance of plasma products from all female donors as well as testing for HLA and neutrophil antibodies should be recommended or implemented as measures to prevent TRALI within our national blood programme.