Association of C and E expression with RHD alleles with the potential of anti-D immunization

LUJÁN M; TRUCCO BOGGIONE C; GARCÍA BORRÁS S; BIONDI C; RACCA A; COTORRUELO C

Buenos Aires

Congreso; 1st French-Argentine Immunology Congress. LVIII Reunión Annual de la Sociedad Argentina de Inmunología; 2010

Sociedad Argentina de Inmunología

The Rh system is highly polymorphic and one of the most clinically significant blood group in transfusion medicine. Reliable routine D typing approaches should be performed to identify some D variants that can cause anti-D alloimmunization upon transfusion. However, extremely weak D expression, termed DEL, may be confound from truly D negative units and used for D negative recipients. The aim of this study was to investigate the presence of RHD alleles in serologically D negative individuals. Blood samples from 661 D negative blood donors were studied. The Rh phenotype was performed by hemmaglutination. The presence of the D antigen was further analyzed by the indirect antiglobulin test. DNA samples were initially screened using a multiplex PCR strategy that amplifies intron 4 and the 3’ unstranslated region of the RHD gene. Samples carrying RHD specific fragments were further studied by RHD exon scanning. Uncharacterized samples were analyzed by microarray strategies and sequencing. In the 661 D negative samples studied, 69 (8.93 %) were C positive or E positive. Molecular studies showed that 8 samples carried RHD specific fragments. In 3 C positive samples we detected RHD-RHCE hybrid alleles: one RHD-CE(3-7)-D and 2 RHD-CE(3-9)-D. One C positive sample carried the RHD(361del11) allele. All these alleles were reported to be associated with a D negative phenotype. We also found one C positive sample with the characteristic polymorphism of a DEL(M295I) phenotype and 3 E positive samples carrying an allele that had never been described, named RHD(46T>C). These new variants were serologically retested by adsorption elution assays and proved to be DEL phenotypes. These findings suggest that clinically important variants in D negative individuals are associated with C or E antigens. The detection of DEL alleles in donors is essential to minimize the risk of anti-D alloimmunization.