Rh immunization by the partial D antigen of category DVa

Area of Science:

• Immunology
• Transfusion Medicine
• Maternal-Fetal Medicine

Background:

• RhD incompatibility is a significant concern in pregnancy, potentially leading to hemolytic disease of the fetus and newborn (HDFN).
• Rh immunoglobulin (RhIG) prophylaxis is administered to D-negative mothers to prevent alloimmunization against the RhD antigen.
• Partial D variants represent a complex subset of RhD antigens that may pose challenges in RhD typing and RhIG efficacy.

Observation:

• A D-negative mother developed anti-D antibodies during her second pregnancy.
• This occurred after receiving RhIG post-delivery of her first RhD-positive child.
• Her second child exhibited moderate neonatal jaundice, requiring phototherapy.

Findings:

• The red blood cells of the father and the first child were identified as carrying a partial D antigen, specifically the DVa subtype.
• This DVa partial D antigen was implicated as the causative agent for anti-D production in the mother.
• Testing revealed that six different Rh immunoglobulin batches reacted with DVa red blood cells, suggesting potential variability in RhIG effectiveness against this specific partial D variant.

Implications:

• This case represents the first documented instance of a partial D antigen (DVa) of fetal origin stimulating anti-D production in a D-negative mother.
• It underscores the importance of considering partial D antigens in RhD alloimmunization, even in mothers who have received RhIG.
• Further investigation is warranted to understand the immunogenicity of various partial D antigens and to optimize RhIG strategies for preventing RhD alloimmunization in diverse populations.