Blood group Rh(D) antigen (RhD)

The Blood group Rh(D) antigen is a complex, multi-pass transmembrane protein expressed exclusively on the surface of erythrocytes (UniProt: P18577). As the most immunogenic antigen within the Rhesus blood group system, it is a primary driver of alloimmunization during pregnancy and blood transfusions (StatPearls: Rh Blood Group System). While its exact physiological role is still being elucidated, it is believed to maintain red blood cell membrane structural integrity and participate in the transport of ammonium ions (NCBI Gene: 6000). In clinical practice, RhD is the target of Rho(D) immune globulin, which is administered to Rh-negative individuals to prevent the formation of anti-D antibodies, thereby avoiding hemolytic disease of the fetus and newborn (HDFN) (PubMed: 29262354). Additionally, it serves as a therapeutic target in immune thrombocytopenic purpura (ITP), where anti-D antibodies are used to induce a controlled hemolysis that saturates splenic Fc receptors, sparing the patient's platelets from destruction (StatPearls: Immune Thrombocytopenic Purpura). The protein's absence or alteration defines the Rh-negative phenotype, which is found in approximately 15% of the Caucasian population (Wikipedia: Rh blood group system). Management of RhD-related conditions remains a cornerstone of modern obstetric care and transfusion safety protocols.

Other names

Rh polypeptide 1Rhesus D antigenCD240DRh blood group D antigenRHD

Passive immunization to prevent maternal sensitization to fetal RhD-positive red blood cells; in ITP, it causes competitive inhibition of Fc receptors on splenic macrophages by coating RhD-positive erythrocytes (StatPearls: Rh Blood Group System).