Platelet Autoantibodies

Immune response against platelet surface antigens results in antiplatelet antibodies production, which is the basis for idiopathic (ITP), drug-induced, post transfusion, and neonatal alloimmune thrombocytopenia (NAIT), where ITP is the most common disease. The antiplatelet antibodies are mainly immunoglobulin (Ig)G, mostly against glycoproteins (GP) – GPIIb/IIIa and GPIb/IX. Antibody-coated platelets bind antigen-presenting cells through Fcγ receptors in the spleen and by the mononuclear phagocyte system. The pathogenesis of ITP was first explained by immune-mediated platelet destruction, but increased evidence indicates that it is also due to immune-mediated decreased platelet production and decreased platelet survival. The diagnosis is based on clinical and serologic findings. Various techniques have been developed to detect platelet autoantibodies to facilitate the diagnosis of ITP, such as fluorescence flow cytometry, immunoblot, immunoprecipitation, immunobead, and monoclonal antibody-specific immobilization of antibodies (MAIPA).