Establishment of Flow Cytometric Immunobead Array for Detecting Plasma Von Willebrand Factor Activity and Its Clinical Application in the Prognosis of Ischemic Stroke

OBJECTIVE: To establish a novel flow cytometric immunobead array (FCIA) for detecting plasma von Willebrand factor activity (vWF:GPIbR) and apply it in ischemic stroke (IS). METHODS: Microspheres coated with anti-human platelet glycoprotein Ibα (GPIbα) monoclonal antibody SZ151 IgG, were incubated with recombinant fragment of GPIbα, then added ristocetin and plasma, finally incubated with FITC-conjugated sheep-anti-human vWF IgG polyclonal antibody, and detected by flow cytometry. vWF antigen (vWF:Ag), vWF:GPIbR, and vWF collagen binding assay (vWF:CB) were also included for evaluating vWF levels in IS patients. RESULTS: The intra-assay coefficient variations (CVs) and inter-assay CVs of FCIA were 7.7% and 13.5%, respectively. The slope of the linear regression was 0.9739 (r=0.855, P<0.001), and the Bland-Altman bias was 9.95%, indicating a good correlation between FCIA and ELISA. The FCIA had better sensitivity, specificity and accuracy as compared with those by ELISA (P<0.05). The levels of vWF:Ag, vWF:GPIbR and vWF:CB in IS patients were significantly higher in comparison with those in healthy controls (H=7.8, 6.4, 6.2, respectively, P<0.01), the level of vWF:GPIbR in IS patients positively correlated with levels of vWF:Ag, high-sensitivity C-reactive protein, Autar score and hospitalization time. CONCLUSION: The FCIA for detecting plasma vWF:GPIbR is more specific and accurate than ELISA. The vWF:GPIbR is involved in the paroxysm of IS, which could be used to evaluate the risk of thrombosis in IS patients.