A comprehensive analysis of DEL types: partial DEL individuals are prone to anti-D alloimmunization.
BACKGROUND
The D antigen of the polymorphic Rh blood group system is of particular clinical importance regarding transfusion- and pregnancy-induced alloimmunization. Different RhD variants with specific clinical implications have been characterized. The least expressed D variants collectively called DEL are serologically detectable only by adsorption-elution techniques, with so far only poorly defined antigenic properties.


METHODS
A comprehensive immunohematologic analysis of five of the six currently known DEL genotypes was performed. DEL phenotypes associated with the RHD(M295I), RHD(IVS3+1g>a), RHD(K409K), RHD(X418L), or RHD(IVS5-38del4) allele were characterized with extended serology and flow cytometry.


RESULTS
Epitope mapping with adsorption-elution revealed a prominent D epitope loss in the RHD(IVS3+1g>a)-associated DEL phenotype, whereas in the other four DEL types no signs of qualitative D antigen alteration were detected. The observation of alloanti-D in two RHD(IVS3+1g>a) cases confirmed the partial nature of this DEL phenotype. The RHD(M295I) phenotype exhibited the highest D antigen expression among all investigated DEL types, as determined by a semiquantitative adsorption-elution approach and flow cytometry.


CONCLUSIONS
In conclusion, evidence is provided that different DEL genotypes code either for partial or complete D antigen expression and that this finding is clinically relevant.
Körmöczi
Günther F
GF
Department of Blood Group Serology and Transfusion Medicine, Medical University of Vienna, Vienna, Austria. guenther.koermoeczi@meduniwien.ac.at
Gassner
Christoph
C
Shao
Chao-Peng
CP
Uchikawa
Makoto
M
Legler
Tobias J
TJ
D000328:Adult; D000483:Alleles; D000911:Antibodies, Monoclonal / Q000276:immunology; D044466:Asian People / Q000235:genetics; D001787:Blood Group Incompatibility / Q000209:etiology* / Q000276:immunology / Q000517:prevention & control; D001788:Blood Grouping and Crossmatching / Q000379:methods; D002648:Child; D018604:Epitope Mapping; D000939:Epitopes / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology; D004910:Erythrocyte Membrane / Q000276:immunology; D005260:Female; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000235:genetics*; D005838:Genotype; D006239:Haplotypes / Q000235:genetics; D006801:Humans; D007163:Immunosorbent Techniques; D007518:Isoantibodies / Q000096:biosynthesis* / Q000276:immunology; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D012203:Rh Isoimmunization / Q000453:epidemiology / Q000209:etiology / Q000235:genetics*; D012204:Rh-Hr Blood-Group System / Q000032:analysis / Q000096:biosynthesis / Q000145:classification / Q000235:genetics* / Q000276:immunology; D018029:Rho(D) Immune Globulin; D012698:Serologic Tests; D044465:White People / Q000235:genetics
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