Rapidly freeze‐dried human red blood cells for pre‐transfusion alloantibody testing reagents

Abstract Prior to transfusion of red blood cells (RBCs), recipients must be tested for the presence of alloantibodies to avoid immune complications. Liquid‐preserved reagent RBCs with known blood group antigen phenotypes are used for testing. However, these reagents have practical constraints, including limited shelf‐life and require constant refrigeration. To address these issues, we explore the effects of rapid freeze‐drying conditions with trehalose cryoprotectant (0.1–1 M concentrations) on human RBCs and storage of freeze‐dried RBCs (FDRBCs) at room temperature (RT) for up to 12 months. We report that rapid freeze‐drying of RBCs for 2.5 hr with 0.5 M trehalose achieves recoverable cells with near‐normal morphological shape, although size‐reduced. The FDRBCs are metabolically active and functional in antibody‐agglutination tests by the column agglutination test (CAT) for ABO and Rhesus‐D blood group antigens. Expression of the Duffy blood group protein (CD234) decreases by 50% after freeze‐drying RBCs. The initial recovery rate is ≤25%; however, 43% of these FDRBCs are still recoverable after RT storage for 12 months. In this proof‐of‐principle study, we show that rapid freeze‐drying can stabilize RBCs. Further refinements to improve the recovery rate and preservation of antigenic epitopes will make FDRBCs a practical alternative source of reagent RBCs for pre‐transfusion alloantibody identification.