Cryopreservation of Genotyped ABO Subgroup RBCs for Quality Assurance of ABO Grouping Reagents.

BACKGROUND: Quality assurance of newly developed or manufactured blood grouping reagents with reagent red blood cells (RBCs) is crucial in the process of product approval by governmental agency. However, RBCs with rare blood group are not easily available in the fresh state. We investigated the feasibility of cryopreserved and genotyped ABO subgroup RBC reagents for quality assurance purpose.

METHODS: We obtained RBCs from 10 volunteers with ABO subgroup phenotypes. The ABO genotypes and alleles were analyzed by the sequencing of ABO exon 6 and 7. Using the 40% wt/vol high-glycerol method, RBC units were cryopreserved as reagent RBCs into separate cryovials at -80°C. The potency titrations were performed before and after cryopreservation for 6 months and 2 years to evaluate the stability of ABO antigens.

RESULTS: ABO genotypes of cryopreserved RBCs were cis-AB01/O01 (n=2), cis-AB01/B101 (n=1), Aw10/B101 (n=2), A201/A201 (n=1), A205/B101 (n=1), A102/B112 (n=1), and A101/B306 (n=1). These ABO subgroup alleles are exclusively present in East-Asian population except for the known ABO*A201 allele. The potency titers of cryopreserved RBCs were not significantly different between pre-freezing and post-freezing.

CONCLUSIONS: The national performance evaluation of ABO blood grouping reagents could be performed with cryopreserved and genotyped reagent RBCs.