HLA selected red cell transfusions to prevent HLA sensitisation: a prospective, double-blinded, randomised controlled trial.

Human Leucocyte Antigen (HLA) sensitisation following red cell transfusion can disrupt planned transplantation and impair outcomes. We conducted a prospective, randomised controlled, double blinded, parallel arm study to evaluate the efficacy of HLA selected red cell transfusions in preventing blood donor specific HLA antibodies (bDSA). Participants were recruited to two groups: adults requiring transfusion or surgery, and paediatric cardiac surgery patients; and randomised to receive red cells selected for HLA compatibility from HLA-typed blood donors, or unselected red cells. Exclusion criteria included recent transfusions, immunoglobulin or B cell depleting treatments, and requirement for additional blood products. The primary outcome was cumulative incidence of de novo bDSA, by HLA antibody testing pre- and post-transfusion. 73 adult participants and 68 paediatric participants were randomised, with 26 and 52 respectively completing the study. Many randomised participants (40% and 59% in adult and paediatric groups respectively) received non-trial products, and there was no significant difference between treatment groups in the intention-to-treat analyses. No de novo bDSA were detected in participants who had received trial products only, while de novo bDSA were detected in participants who received unselected red cell products. Larger studies could confirm the potential to avoid HLA sensitisation by blood donor selection.