HPA-1a-specific B-lymphocyte

HPA-1a-specific B-lymphocytes are a specialized population of maternal immune cells responsible for the production of alloantibodies against Human Platelet Antigen-1a (HPA-1a). In pregnancies where the mother is HPA-1a-negative (typically HPA-1b1b) and the fetus is HPA-1a-positive, these B cells can become sensitized to fetal platelets, leading to the secretion of anti-HPA-1a IgG antibodies (1.1.1, 1.1.3). These antibodies cross the placenta via the neonatal Fc receptor (FcRn) and mediate the destruction of fetal platelets, a condition known as Fetal and Neonatal Alloimmune Thrombocytopenia (FNAIT) (1.1.2, 1.4.1). FNAIT is a serious condition that can lead to severe fetal thrombocytopenia and life-threatening intracranial hemorrhage (1.2.1, 1.3.5). Therapeutic targeting of HPA-1a-specific B-lymphocytes aims to prevent or eliminate the source of pathogenic antibodies. Investigational approaches include antigen-specific chimeric fusion proteins that bind to the B-cell receptor (BCR) of these cells to induce depletion, as well as Chimeric Autoantibody Receptor (CAAR) T cells designed to selectively kill HPA-1a-reactive B cells (1.3.1, 1.4.1). Other strategies, such as the prophylactic administration of anti-HPA-1a antibodies (e.g., RLYB212), work by clearing fetal platelets from maternal circulation before B-cell sensitization can occur (1.3.3, 1.3.4). These targeted therapies offer the potential for antigen-specific treatment without the broad immunosuppressive risks associated with current standards of care like intravenous immunoglobulin (IVIG) (1.3.1).

Other names

HPA-1a-specific B cellAnti-HPA-1a antibody-producing B cellHPA-1a-reactive B cell

Selective depletion of HPA-1a-specific B cells via antigen-mimetic binding to the B-cell receptor to eliminate the source of pathogenic alloantibodies.