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

Abstract

Background: 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).

Methods: 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.

Results: 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<0.01). In ROC analysis, values of the area under the curve were 0.89, 0.82, 0.93, 0.94 and 0.95, respectively. In ITP diagnosis, the FCIA assay with these five antibodies had better sensitivity and accuracy than the MAIPA assay (96% vs. 44% in sensitivity; 80.9% vs. 64.7% in accuracy, p<0.01).

Conclusion: FCIA assays with multiple antibodies against platelet GPs may be used to improve the diagnosis of ITP in hospitals.