RhD Specific Antibodies Are Not Detectable in HLA-DRB1*1501 Mice Challenged with Human RhD Positive Erythrocytes

The ability to study the immune response to the RhD antigen in the prevention of hemolytic disease of the fetus and newborn has been hampered by the lack of a mouse model of RhD immunization. However, the ability of transgenic mice expressing human HLA DRB1(*)1501 to respond to immunization with purified RhD has allowed this question to be revisited. In this work we aimed at inducing anti-RhD antibodies by administering human RhD(+) RBCs to mice transgenic for the human HLA DRB1(*)1501 as well as to several standard inbred and outbred laboratory strains including C57BL/6, DBA1/J, CFW(SW), CD1(ICR), and NSA(CF-1). DRB1(*)1501 mice were additionally immunized with putative extracellular immunogenic RhD peptides. DRB1(*)1501 mice immunized with RhD(+) erythrocytes developed an erythrocyte-reactive antibody response. Antibodies specific for RhD could not however be detected by flow cytometry. Despite this, DRB1(*)1501 mice were capable of recognizing immunogenic sequences of Rh as injection with Rh peptides induced antibodies reactive with RhD sequences, consistent with the presence of B cell repertoires capable of recognizing RhD. We conclude that while HLA DRB1(*)1501 transgenic mice may have the capability of responding to immunogenic sequences within RhD, an immune response to human RBC expressing RhD is not directly observed.