Anti-HrB and anti-hrb revisited.

BACKGROUND

Since their description in the 1970s, anti-Hr(B) (antibody against a high-prevalence Rh antigen) and anti-hr(B) (anti-e-like antibody) are still a subject of debate about representing two aspects of a global immune response or being two independent antibodies.

STUDY DESIGN AND METHODS

The aim of this study was to evaluate the immune response against the antigens of Rh system of 30 individuals presenting a hr(B)(RH31)- phenotype. Genomic analysis of RH genes was performed in all individuals.

RESULTS

Among the 30 individuals, 27 had a Hr(B)(RH34)- phenotype. No immunization against Rh antigens was found in 16 individuals. Three individuals made anti-D only, whereas six individuals made anti-Hr(B) (four with anti-hr(B) and two without anti-hr(B)) and two individuals made anti-hr(B) without anti-Hr(B). Among the 30 individuals, three had a Hr(B)+ phenotype. No immunization against Rh antigens was found in one individual, whereas two individuals made anti-hr(B); the genomic analysis of selected individuals showed the presence of a (C)ce(s) haplotype, either Type 1 or Type 2, and a DIII Type 5 ce(s) haplotype, in the homozygous state, in compound heterozygosity with each other or in heterozygosity with a DcE haplotype. Genomic data were in accordance with serologic data.

CONCLUSION

Our data provide the evidence that anti-Hr(B) and anti-hr(B) are independent antibodies, defining two different specificities. These antibodies may be produced by individuals expressing variants of RhCE protein. Serologic and molecular data indicate that e antigen encoded by the (C)ce(s) haplotype is a partial antigen. In individuals carrying a (C)ce(s) haplotype, the risk and the type of alloimmunization to Rh antigens are related to the second Rh haplotype.