Novel weak D types 31 and 32: adsorption-elution-supported D antigen analysis and comparison to prevalent weak D types.
BACKGROUND
Weak D types are thought to express rather quantitative than qualitative D antigen variants. Distinct type-specific phenotypes and weak D cases with anti-D alloimmunization, however, suggest a variable degree of D antigen alteration.


METHODS
Variant D types were investigated by use of molecular typing, RHD sequencing, extended serologic D antigen investigations, and flow cytometric D antigen density determination.


RESULTS
Two novel weak D types were discovered, termed weak D type 31 and 32 with single RHD nucleotide substitutions coding for amino acid exchanges in predicted intracellular RhD polypeptide stretches, with antigen densities of approximately 130 and 50 D sites per red blood cell, respectively. Adsorption-elution technique-supported D epitope mapping of these two weak D types, the recently described weak D type 26, and of the most common Central European weak D types (weak D types 1, 2, 3, 4.0, and 4.1) demonstrated the expression of all tested D epitopes. In contrast, a distinct D epitope loss was detected in weak D type 15 and partial D control samples.


CONCLUSIONS
All novel and prevalent weak D types expressed all tested D epitopes. Our results indicate that adsorption-elution techniques may be of advantage whenever D epitope loss is suspected in extremely weak D variants.
Körmöczi
Günther F
GF
Department of Blood Group Serology and Transfusion Medicine, Medical University of Vienna, Vienna, Austria. guenther.koermoeczi@meduniwien.ac.at
Förstemann
Elisabeth
E
Gabriel
Christian
C
Mayr
Wolfgang R
WR
Schönitzer
Diether
D
Gassner
Christoph
C
D000328:Adult; D000483:Alleles; D019943:Amino Acid Substitution; D000911:Antibodies, Monoclonal / Q000276:immunology; D000937:Antigen-Antibody Reactions; D001317:Austria; D001483:Base Sequence; D001782:Blood Donors; D001788:Blood Grouping and Crossmatching / Q000379:methods; D000939:Epitopes / Q000235:genetics / Q000276:immunology; D004910:Erythrocyte Membrane / Q000276:immunology; D005260:Female; D005858:Germany; D006801:Humans; D007163:Immunosorbent Techniques; D007518:Isoantibodies / Q000276:immunology; D008297:Male; D008403:Mass Screening; D008969:Molecular Sequence Data; D010641:Phenotype; D017354:Point Mutation; D012203:Rh Isoimmunization / Q000209:etiology / Q000235:genetics / Q000276:immunology; D012204:Rh-Hr Blood-Group System / Q000032:analysis / Q000737:chemistry / Q000145:classification / Q000235:genetics* / Q000276:immunology; D018029:Rho(D) Immune Globulin; D017422:Sequence Analysis, DNA; D009626:Terminology as Topic
D000911:Antibodies, Monoclonal; D000939:Epitopes; D007518:Isoantibodies; C061961:RHO(D) antibody; D012204:Rh-Hr Blood-Group System; D018029:Rho(D) Immune Globulin; C026410:Rho(D) antigen