Weak D alleles express distinct phenotypes.
The weak D phenotype is caused by many different RHD alleles encoding aberrant RhD proteins, raising the possibility of distinct serologic phenotypes and of anti-D immunizations in weak D. We reported 6 new RHD alleles, D category III type IV, DIM, and the weak D types 4.1, 4.2.1, 4.2.2, and 17. The immunohematologic features of 18 weak D types were examined by agglutination and flow cytometry with more than 50 monoclonal anti-D. The agglutination patterns of the partial D phenotypes DIM, D(III) type IV, and D(IV) type III correlated well with the D epitope models, those of the weak D types showed no correlation. In flow cytometry, the weak D types displayed type-specific antigen densities between 70 and 4000 RhD antigens per cell and qualitatively distinct D antigens. A Rhesus D similarity index was devised to characterize the extent of qualitative changes in aberrant D antigens and discriminated normal D from all tested partial D, including D category III. In some rare weak D types, the extent of the alterations was comparable to that found in partial Ds that were prone to anti-D immunization. Four of 6 case reports with anti-D in weak D represented auto-anti-D. We concluded that, in contrast to previous assumptions, most weak D types, including prevalent ones, carry altered D antigens. These observations are suggestive of a clinically relevant potential for anti-D immunizations in some, but not in the prevalent weak D types, and were used to derive an improved transfusion strategy in weak D patients. (Blood. 2000;95:2699-2708)
Wagner
F F
FF
Abteilung Transfusionsmedizin, Universitätsklinikum Ulm and DRK-Blutspendedienst Baden-Württemberg, Institut Ulm, Ulm, Germany.
Frohmajer
A
A
Ladewig
B
B
Eicher
N I
NI
Lonicer
C B
CB
Müller
T H
TH
Siegel
M H
MH
Flegel
W A
WA
D000483:Alleles; D000911:Antibodies, Monoclonal / Q000276:immunology; D000918:Antibody Specificity; D005260:Female; D006801:Humans; D007518:Isoantibodies / Q000276:immunology; D008297:Male; D012204:Rh-Hr Blood-Group System / Q000235:genetics* / Q000276:immunology; D018029:Rho(D) Immune Globulin
D000911:Antibodies, Monoclonal; D007518:Isoantibodies; C061961:RHO(D) antibody; D012204:Rh-Hr Blood-Group System; D018029:Rho(D) Immune Globulin; C026410:Rho(D) antigen