Survival of transfused red blood cells from a donor with alpha-thalassemia trait in a recipient with sickle cell disease

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.

Post-transfusion biotin-labeled red blood cell survival studies in pediatric sickle cell disease with antibodies of uncertain significance

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 (T50) 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.

The impact of the COVID-19 pandemic on source plasma donations

While the COVID-19 pandemic has impacted many aspects of healthcare, including routine blood donations, the impact of COVID-19 on the donation of source plasma critical to many aspects of patient care, including apheresis procedures, has been more difficult to define. As production of plasma-derived medicinal products (PDMPs) can take up to a year, shortages in source plasma donations may not be immediately appreciated. Given current shortages in PDMPs, in particular albumin, we examined the impact of COVID-19 on source plasma donations. Our data demonstrate that source plasma donations were disproportionately impacted by COVID-19 and that these shortages remained until the latter half of 2022. Given the time delay in PDMP manufacturing, these results suggest that while source plasma donation levels are returning to pre-pandemic levels, shortages in PDMPs may not be quickly overcome. These results also highlight the unique vulnerabilities in plasma sourcing that may continue to manifest as PDMP shortages for years to come.

Creation and maintenance of Helix, a Web based database of medical genetics laboratories, to serve the needs of the genetics community

Helix (healthlinks.washington.edu/helix) is a web accessible database that serves as the main U.S. directory of laboratories offering genetic testing. The database was designed to address the previously unmet need for a centralized, continuously updated source of information about clinical and research genetic testing to keep pace with the rapid rate of gene discovery resulting from the Human Genome Project. The Helix project began in 1992 at the University of Washington and Children's Hospital and Regional Medical Center. It has evolved from a single user stand alone relational database to a fully Web enabled database queried and maintained via the web and linked to other web accessible genomic databases. As of February, 1998 it lists more than 500 diseases and 290 laboratories, with over 5,200 registered users making approximately 250 queries/day (90% via the Internet). We describe the iterative design, implementation, population and assessment of the database over a six year period.