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Background: Post-transfusion survival of donor red blood cells (RBCs) is important for effective chronic transfusion therapy in conditions including sickle cell disease (SCD). Biotin labeling RBCs allows direct in vivo measurement of multiple donor RBC units simultaneously post-transfusion., Study Design and Methods: In an observational trial of patients with SCD receiving monthly chronic transfusion therapy, aliquots of RBCs from one transfusion episode were biotin-labeled and infused along with the unlabeled RBC units. Serial blood samples were obtained to measure RBC survival. Donor units were tested for RBC indices, hemoglobin fractionation, and glucose-6-phosphate dehydrogenase (G6PD) enzyme activity. For microcytic donor RBCs (MCV < 70 fL), HBA1 and HBA2 genetic testing was performed on whole blood., Results: We present one recipient, a pediatric patient with SCD and splenectomy who received two RBC units with aliquots from each unit labeled at distinct biotin densities (2 and 18 μg/mL biotin). One donor unit was identified to have microcytosis (MCV 68.5 fL after biotinylation); whole blood sample obtained at a subsequent donation showed 2-gene deletion alpha-thalassemia trait (ɑ- 3.7kb /ɑ- 3.7kb ) and normal serum ferritin. G6PD activity was >60% of normal mean for both. The RBCs with alpha-thalassemia RBC had accelerated clearance and increased surface phosphatidylserine post-transfusion, as compared with the normocytic RBC (half life 65 vs. 86 days, respectively)., Discussion: Post-transfusion RBC survival may be lower for units from donors with alpha-thalassemia trait, although the impact of thalassemia trait donors on transfusion efficacy requires further study., (© 2024 AABB.)

Background: Red blood cell (RBC) antibodies are common in multiply transfused patients with sickle cell disease (SCD). Unlike RBC alloantibodies, the potential of autoantibodies to cause post-transfusion hemolysis may be uncertain. Biotin-labeling provides a direct measurement of red cell survival (RCS) over time, thus can be used to assess the clinical significance of RBC antibodies. Antibodies to biotinylated RBC (B-RBC) occasionally are detected after exposure, which may impact B-RBC survival in subsequent RCS studies., Study Design and Methods: Pediatric patients with SCD receiving monthly chronic transfusions underwent RCS studies, receiving aliquots of allogeneic RBC labeled at distinct densities of biotin (2-18 μg/mL). B-RBC survival was followed for 4 months post-transfusion, and B-RBC antibody screening for 6 months. Patients with warm autoantibodies (WAA) or B-RBC antibodies are reported here., Results: RBC antibodies were detected during RCS in four patients: one with WAA, one with WAA followed by B-RBC-specific antibodies, and two with transient B-RBC antibodies within the first 5 weeks of exposure. B-RBC half-lives (T 50 ) ranged 37.6-61.7 days (mean 47.8 days). There was no evidence of increased hemolysis or accelerated B-RBC clearance in the presence of WAA or B-RBC antibodies., Discussion: Biotinylation of allogenic RBC can be used to assess the possible effects of RBC antibodies on transfusion survival in individual cases, particularly when it is uncertain if the detected antibodies may result in hemolysis. In the cases presented here, neither WAA nor B-RBC antibodies were associated with significant shortening of B-RBC survival in individuals with SCD., (© 2024 AABB.)