Anti-human platelet antigen-1a immunoglobulin G (Anti-HPA-1a IgG)

Anti-HPA-1a IgG is a pathogenic maternal alloantibody directed against the Human Platelet Antigen-1a (HPA-1a), which is located on the platelet membrane glycoprotein IIb/IIIa complex (integrin alphaIIb beta3). In HPA-1a negative mothers, exposure to HPA-1a positive fetal platelets during pregnancy can trigger the production of these antibodies, which then cross the placenta and cause the destruction of fetal platelets. This condition, known as Fetal and Neonatal Alloimmune Thrombocytopenia (FNAIT), is a leading cause of severe thrombocytopenia and intracranial hemorrhage in neonates. From a therapeutic perspective, anti-HPA-1a IgG is considered a target for neutralization or accelerated clearance. Current drug development efforts focus on neonatal Fc receptor (FcRn) blockers to reduce maternal antibody levels and prophylactic monoclonal antibodies designed to prevent maternal sensitization by clearing fetal platelets from the maternal circulation.

Other names

Anti-HPA-1a antibodyMaternal anti-HPA-1a IgGAnti-Zw(a) antibodyAnti-Pl(A1) antibody

Therapeutic strategies targeting anti-HPA-1a IgG include the use of FcRn inhibitors to accelerate the clearance of maternal IgG from circulation, or the administration of prophylactic hyperimmune globulins/monoclonal antibodies to prevent maternal sensitization by rapidly clearing HPA-1a positive fetal platelets before an immune response is mounted.