Platelet antibodies and diagnosis of immune-mediated thrombocytopenia

Analysis of platelet antibodies provides valuable support for diagnosis and therapy of platelet-related bleeding disorders. Platelet autoantibodies in duce autoimmune thrombocytopenia and - in very rare cases - platelet dysfun ction. Drug-induced immune thrombocytopenia is caused by drug-dependent ant ibodies, a class of autoreactive antibodies binding to platelets only in th e presence of the offending drug. Immunologically induced refractoriness to platelet transfusions is most commonly caused by alloimmunization against HLA class I antigens. In rare cases, additional platelet-specific antibodie s occur. Alloantibodes against polymorphic determinants on glycoproteins II b/IIIa, Ia/IIa and - rarely - Ib/IX play a central role in the pathogenesis of fetal and neonatal alloimmune thrombocytopenia. Posttransfusion purpura is a rare transfusion reaction affecting almost exclusively female patient s.