HemosIL VWF:GPIbR Assay Has a Greater Sensitivity than VWF:RCo Technique to Detect Acquired von Willebrand Syndrome in Myeloproliferative Neoplasms.

ABSTRACT

BACKGROUND: Acquired von Willebrand syndrome (AVWS) is frequent in patients with myeloproliferative neoplasms (MPNs). For von Willebrand factor (VWF) functional evaluation, ristocetin cofactor activity by aggregometry (VWFRCo) is considered the gold standard but has limitations, and automated activity measurement has been developed such as the HemosIL VWFRCo Werfen with particle agglutination (VWFGPIbR). OBJECTIVES: To evaluate the performance of VWFGPIbR with HemosIL VWFRCo Werfen (VWFGPIbR) versus VWFRCo in patients with thrombocytosis in the context of MPNs (T-MPNs) and in patients with secondary thrombocytosis (ST). METHODS: MPN patients with thrombocytosis >450 G/L (T-MPNs) were compared with patients with ST due to inflammation or iron deficiency. VWF activity (VWFAct) was analyzed using VWFRCo or VWFGPIbR. VWF analysis was completed by analysis of VWF multimers and VWF collagen binding (CB) assay (VWFCB). RESULTS: A total of 33 T-MPNs and 18 ST patients were included. Compared with aggregometry, evaluation of VWFAct by VWFGPIbR led to lower values in T-MPN patients, but also in ST patients. Interestingly, although the VWFRCo/VWFAg ratio did not reveal differences between T-MPNs and ST patients, the VWFGPIbR/VWFAg ratio analysis allowed us to suspect AVWS only in T-MPN patients. Using the distribution of VWF multimer analysis and VWFCB, we here demonstrated that VWFGPIbR allows AVWS diagnosis in nine T-MPNs as opposed to aggregometry. CONCLUSION: Evaluation of VWFAct using VWFGPIbR has a greater sensitivity compared with aggregometry to detect AVWS in T-MPN patients.