By using the modified monoclonal antibody immobilization of platelet antigen (MAIPA) assay, it is possible to identify glycoprotein (GP) specific autoantibodies, such as GPVI, GPIb/IX, and GPIIb/IIIa autoantibodies, in the majority of platelet or plasma eluates from ITP patients. Here, GP6 is linked to autoimmune thrombocytopenic purpura.