Detection of autoantibodies against platelet glycoproteins in patients with immune thrombocytopenic purpura by flow cytometric immunobead array

The goal of this study is to develop a flow cytometric immunobead array (FCIA) assay to detect platelet autoantibodies commonly present in bleeding patients with immune thrombocytopenic purpura (ITP). Polystyrene microbeads coated with antibodies against human platelet glycoproteins (GPs) IX (SZ1), Ib (SZ2), IIIa (SZ21), IIb (SZ22), and P-selectin (SZ51) were incubated with platelet lysate from 50 ITP patients and 86 controls. The platelet antigen–autoantibody complexes were detected by flow cytometry using an FITC-labeled antibody. The results were compared with that of a monoclonal antibody immobilization of platelet antigen (MAIPA) assay. By FCIA, platelet autoantibodies against GPIb, GPIIb, GPIIIa, GPIX and P-selectin were detected in ITP patients. Mean fluorescent intensity values with antibodies SZ1, SZ2, SZ21, SZ22 and SZ51 were all higher in ITP patients than controls (p values