Blood group Rh(D) polypeptide (RhD) (RhD)

The Blood group Rh(D) polypeptide (RhD) is a multi-pass transmembrane protein expressed exclusively on the surface of red blood cells and their precursors (UniProt: P18577). It is the most clinically significant antigen within the Rhesus blood group system due to its high immunogenicity and its role in transfusion medicine (StatPearls: Rh Incompatibility). Biologically, RhD is part of a macromolecular complex that maintains the structural integrity of the erythrocyte membrane and is involved in the transport of ammonium ions and possibly carbon dioxide (NCBI Gene: 6007). In clinical practice, RhD is the primary target for Rho(D) immune globulin, which is administered to Rh-negative pregnant women to prevent hemolytic disease of the newborn by clearing Rh-positive fetal cells from maternal circulation (PubMed: PMID 17631291). It is also utilized as a decoy target in the treatment of immune thrombocytopenic purpura (ITP) to reduce the destruction of platelets by saturating splenic macrophages (DrugBank: DB00059). Understanding RhD status is essential for safe blood transfusions and prenatal care to avoid life-threatening alloimmunization.

Other names

Rh blood group D antigenCD240DRhesus D antigenRh polypeptide 1RH1RhD antigen

Rho(D) immune globulin acts via antibody-mediated immune suppression (AMIS). It binds to RhD antigens on fetal red blood cells in the maternal circulation, leading to their sequestration and clearance in the spleen before maternal B-cells can be sensitized (StatPearls: Rh Incompatibility). In the treatment of immune thrombocytopenic purpura (ITP), the anti-D antibodies coat the patient's own RhD-positive red blood cells; these coated cells then occupy the Fc receptors on splenic macrophages, preventing the macrophages from binding and destroying autoantibody-coated platelets (PubMed: PMID 12149211).