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Primary anti‐D immunization by weak D type 2 RBCs
Author(s) -
Flegel W.A.,
Khull S.R.,
Wagner F.F.
Publication year - 2000
Publication title -
transfusion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.045
H-Index - 132
eISSN - 1537-2995
pISSN - 0041-1132
DOI - 10.1046/j.1537-2995.2000.40040428.x
Subject(s) - antigen , allele , phenotype , antibody , isoantibodies , microbiology and biotechnology , immunization , biology , immunology , gene , genetics
BACKGROUND: D is the most immunogenic blood group antigen. In about 0.4 percent of whites, D is expressed on RBCs in a weak form. Recently, it was found that the weak D phenotypes are caused by a large number of distinct RHD alleles generally encoding altered D proteins. No particular molecular weak D type has yet been shown to induce anti‐D. The threshold of D antigen density required for anti‐D immunization is not known. CASE REPORT: A 72‐year‐old D– white man received apparently D– RBCs. Nineteen days later, he developed a positive DAT, and anti‐D was found in his serum and an eluate from his RBCs. One donor was found to be D+ with a weak D type. The weak D type was determined by RHD exon 9‐specific nucleotide sequencing from genomic DNA. The transfusion recipient showed alloanti‐D. Ten months later, anti‐D but no other antibody was detectable; the DAT was negative and the eluate was nonreactive. The donor of the incriminated unit was D+ (ccDEe) with weak D due to the weak D type 2 allele, expressing about 450 D antigens per RBC. CONCLUSION: This case provides formal proof that RBCs of weak D type 2 phenotype may cause alloanti‐D immunization. Among the more prevalent weak D types in whites, weak D type 2 has the lowest D antigen density. Thus, units of blood from donors of the weak D type 2 phenotype should be labeled D+; the weak D type 2 phenotype may be useful for quality assurance.