title: Anti-D immunization by DEL red blood cells.
abstract: BACKGROUND
  No data are available on the immunogenicity of extremely weak D variants called DEL. Evaluation of alloanti-D formation in a D- female patient after transfusion of apparently D- blood from an Austrian donor led to discovery of a so far unknown DEL type.
  
  
  METHODS
  Standard blood group serologic methods were applied. Molecular typing, RHD sequencing, and D epitope mapping was performed and the absolute D antigen density determined.
  
  
  RESULTS
  After transfusion of RBCs typed D- by routine serology, the recipient developed alloanti-D. Further evaluation with an indirect antiglobulin test confirmed donor RBCs to be D-. Molecular typing, however, demonstrated the presence of the RHD gene in one donor, and RHD sequencing revealed a deletion of four nucleotides in RHD intron 5 (RHD IVS5-38del4) as the only difference compared to the normal RHD gene. Adsorption-elution techniques demonstrated a DEL phenotype without apparent loss of D epitopes.
  
  
  CONCLUSIONS
  This study documents the clinical significance of the DEL phenotype in blood units that was capable of inducing anti-D in a recipient. Qualitative data are provided on D epitope expression in DEL RBCs.
authors.affiliation: Department of Blood Group Serology and Transfusion Medicine, Medical University of Graz, Graz, Austria. thomas.wagner@meduni-graz.at
authors.forename: Thomas
authors.initials: T
authors.lastname: Wagner
authors.forename: Günther F
authors.initials: GF
authors.lastname: Körmöczi
authors.forename: Christoph
authors.initials: C
authors.lastname: Buchta
authors.forename: Maria
authors.initials: M
authors.lastname: Vadon
authors.forename: Gerhard
authors.initials: G
authors.lastname: Lanzer
authors.forename: Wolfgang R
authors.initials: WR
authors.lastname: Mayr
authors.forename: Tobias J
authors.initials: TJ
authors.lastname: Legler
mesh_terms: D000483:Alleles; D001782:Blood Donors; D001803:Blood Transfusion; D000939:Epitopes / Q000276:immunology; D004912:Erythrocytes / Q000276:immunology*; D005260:Female; D006801:Humans; D007438:Introns; D008297:Male; D008875:Middle Aged; D010375:Pedigree; D010641:Phenotype; D012204:Rh-Hr Blood-Group System / Q000235:genetics* / Q000276:immunology*
chemical_list: D000939:Epitopes; D012204:Rh-Hr Blood-Group System; C026410:Rho(D) antigen