OA4‐AM23‐MN‐20 | The American Rare Donor Program: 25 Years of Providing Rare Blood to Alloimmunized Patients
Year: 2023
Type: article
Abstract: Background/Case Studies: As novel RHD alleles are identified, comprehensive genetic and serological descriptions are standard practice.Anti-D reactivity profile and D antigen density testing phenotypically characterizes variant RHD alleles, giving insight on the structural alterations to RhD protein.The flow cytometry D antigen density testing method originally developed in 2000 has remained largely unrevised, utilizing monoclonal anti-Ds not readily available anymore.This method was applied in the 4th International Workshop on Monoclonal Antibodies Against Human Red Blood Cell and Related Antigens, when a standard CcDEe cell with a D antigen density of 27,500 was distributed.An updated flow cytometry assay was developed for the quantitation of erythrocyte D antigen sites using anti-Ds that are commercially available today.We tested the reproducibility of our assay with published D antigen densities.Study Design/Methods: The original standard CcDEe cell, drawn and frozen in 2003, and a fresh whole blood donation from the same individual, drawn in 2022, was obtained for testing both the absolute and relative D antigen density.The absolute D antigen density of a new CcDEe cell, homozygous for the RHD gene, was quantified using flow cytometry with fluorescence-labeled standardization beads and used as an internal control.Flow cytometry was performed using an anti-D kit (D-Screen, Diagast) and applied to 5 normal D, 4 partial D, and 11 weak D-type samples, including the 2 novel weak D types 164 and 165.Results/Findings: We determined the absolute D antigen density of the frozen standard CcDEe cell from 2003 as 27,600.The fresh sample from the same individual had an absolute D antigen density of 26,000.The new standard CcDEe cell had an absolute D antigen density of 26,050.The relative D antigen density tested by the anti-D kit differed among normal D, partial D, and weak D samples (Table 1).Conclusions: The new standard CcDEe cell along with the commercially available anti-D kit allowed for differentiation between red cell phenotypes while replicating published D antigen density profiles and providing the first serologic description of weak D types 164 and 165.The updated D antigen quantification assay can be used to study the effects of amino acid substitutions on the RhD phenotype.Applying the revised methodology to RhD, RhCE, and RhAG on the same set of red cells should allow for elucidation of the compositional makeup of the Rh Complex.
Source: Transfusion
DOI: 10.1111/trf.63_17554
Authors: M. Keller, V. Kavitsky, J. Maurer, S. Nance, D. Facey
Institution: American Red Cross
Language: English
Topic: Blood groups and transfusion
Subfield: Hematology
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
OpenAlex ID: W4387572007