Weak and partial D phenotyping: a comparison study between molecular and serologic results.

Variant D antigens can cause variable serologic results when typing with Anti-D reagents. There is limited information regarding the ability of Anti-D reagents to differentiate between D variants defined by genotyping. This study was performed to determine if a panel of 20 U.

Three novel Er blood group system alleles and insights from protein modeling.

Background: The Er blood group system was recently shown to be defined by PIEZO1. The system consists of high prevalence antigens Er, Er3, ERSA, and ERAMA; and low prevalence antigen Er. Er/Er are antithetical with Er(a-b+) defined by the ER*B allele [c.

Evidence that donors with variant RH genotypes are associated with unexpected Rh antibodies.

Background: We previously reported unexpected Rh antibodies in the plasma of patients with sickle cell disease (SCD) that demonstrated common Rh specificities in the absence of transfusion of RBCs positive for that antigen. We hypothesize that these antibodies might result from transfusion of antigen-negative donor units with variant RH genotypes.

Methods: Plasma testing by tube and IgG gel, extended RBC phenotyping, and HEA and RH genotyping were by standard methods.

A novel high-prevalence antigen in the Lutheran system, LUGA (LU24), and an updated, full-length 3D BCAM model.

Background: The basal cell adhesion molecule (BCAM) carries the antigens of the Lutheran (LU, ISBT005) system. We report a novel Lutheran antigen and propose an updated, full-length 3D model of BCAM.

Study Design And Methods: Red blood cell testing, antibody identification, and BCAM genomic DNA sequencing were done by standard methods.

Two new Scianna variants causing loss of high prevalence antigens: ERMAP model and 3D analysis of the antigens.

Background: Scianna (Sc) antigens, seven high and two of low prevalence, are expressed on erythrocyte membrane-associated protein (ERMAP). We investigated SC (ERMAP) in individuals who made antibodies to high prevalence Scianna antigens, and propose a 3D model for ERMAP to precisely localize the residues associated with the known antigens.

Methods: Serological testing and DNA sequencing was performed by standard methods.

International Society of Blood Transfusion Working Party on Red Cell Immunogenetics and Blood Group Terminology Report of Basel and three virtual business meetings: Update on blood group systems.

Background And Objectives: Under the ISBT, the Working Party (WP) for Red Cell Immunogenetics and Blood Group Terminology is charged with ratifying blood group systems, antigens and alleles. This report presents the outcomes from four WP business meetings, one located in Basel in 2019 and three held as virtual meetings during the COVID-19 pandemic in 2020 and 2021.

Materials And Methods: As in previous meetings, matters pertaining to blood group antigen nomenclature were discussed.

YTGT: A new high-prevalence antigen in the Yt blood group system in two unrelated Native Americans and transfusion management.

Background: The Yt system consists of five antigens: antithetical Yt /Yt and the high-prevalence antigens YTEG, YTLI, and YTOT. We investigated a sample from a Native American (NA) female with post-operative anemia and an unidentified antibody who developed rigors, tachycardia, and hypotension on transfusion of incompatible RBCs.

Methods And Materials: Serologic testing methods included LISS, PEG, and IgG gel.

Red Cell Antigens and Antibodies.

Autoimmune hemolytic anemia (AIHA) is caused by the production of "warm-" or "cold-" reactive autoantibodies directed against RBC antigens that may be of undefined specificity, reacting with all RBCs tested or may have an apparent specificity. Autoantibodies may be of IgG, IgM, or rarely IgA isotypes and their production can be triggered by disease, viral infection, or drugs; from breakdown in immune system tolerance to self-antigens; or from exposure to foreign antigens that induce antibodies that cross-react with self-RBC antigens. Increasingly, AIHA is being reported in patients following allogeneic hematopoietic stem cell transplantation and treatment with anti-cancer checkpoint inhibitors.

3D analysis of CROMER (DAF) and a new antigen CRAG.

Background: Cromer antigens are carried on decay accelerating factor (DAF, CD55), for which the crystal structure is available. We investigated two samples with an unidentified antibody to a high prevalence antigen and evaluate the location and characteristics of amino acids associated with antigens on the CD55 by 3D modelling.

Materials And Methods: Antigen typing and antibody identification were by standard methods.

Anti-Emm, a rare specificity to the high-incidence antigen Emm in an Indian patient defining the new blood group system EMM (ISBT042).

A transfusion recipient lacking a high-incidence antigen (HIA) and has corresponding alloantibody pose a problem in providing compatible blood unit. We encountered a patient with an antibody to an HIA that required identification to assess if compatible blood could be organized. A 65-year-old male was posted for coronary artery bypass grafting surgery.

PIGG defines the Emm blood group system.

Emm is a high incidence red cell antigen with eight previously reported Emm- probands. Anti-Emm appears to be naturally occurring yet responsible for a clinically significant acute hemolytic transfusion reaction. Previous work suggests that Emm is located on a GPI-anchored protein, but the antigenic epitope and genetic basis have been elusive.

Use of an in-house trypsin-based method to resolve the interference of daratumumab.

Background: Daratumumab (DARA) is a monoclonal antibody for treatment of plasma cell myeloma targeting CD38, a surface molecule expressed on plasma cells and red blood cells (RBCs). This complicates blood bank testing, requiring dithiothreitol (DTT) to remove DARA interference. A simple in-house method of removing DARA interference without use of DTT, a potentially hazardous chemical, is desirable.

Impact of RHD genotyping on transfusion practice in Denmark and the United States and identification of novel RHD alleles.

Background: Reduced D antigen on red blood cells (RBCs) may be due to "partial" D phenotypes associated with loss of epitope(s) and risk for alloimmunization or "weak" D phenotypes that do not lack major epitopes with absence of clinical complications. Genotyping of samples with weak and discrepant D typing is recommended to guide transfusion and RhIG prophylaxis. The goal was to compare the impact of RHD genotyping on transfusion practice in two centers serving different populations.