A sensitive ristocetin co-factor activity assay with recombinant glycoprotein Ibα for the diagnosis of patients with low von Willebrand factor levels

Augusto B. Federici, Maria T. Canciani, Ileana Forza, Pier Mannuccio Mannucci, Patrizia Marchese, Jerry Ware, Zaverio M. Ruggeri

Research output: Contribution to journalArticlepeer-review

Abstract

Background and Objectives. The assay of ristocetin co-factor activity of von Willebrand factor (VWF:RCo) is used in the screening of patients with suspected von Willebrand's disease (VWD), the most frequent inherited bleeding disorder. A correct diagnosis of VWD relies on platelet agglutination tests that have a low accuracy within and between assays. A more accurate VWF:RCo assay would improve VWD diagnosis and classification. Design and Methods. We describe here an ELISA method in which a recombinant fragment of the α-subunit of platelet glycoprotein Ib-IX-V complex (rGPIbα) is bound to an anti-GPIbα monoclonal antibody immobilized onto microtiter plate wells and which captures plasma VWF in the presence of ristocetin. The results obtained with this ELISA assay were compared blindly with values calculated from the agglutination test in normal subjects (n=60) and in patients with type 1 (n=8), type 2A (n=16), type 2B (n=13), type 2M (n=17) or type 2M Vicenza (n=8) VWD characterized by low VWF levels. Results. The two assays gave similar results in both normal subjects and VWD patients (r=0.93), but the ELISA test had a higher sensitivity (0.1 versus 6.25 U/dL). The repeatability and reproducibility of the ELISA had coefficients of variation of 9% and 10%, respectively, as compared to 14% and 15% for the agglutination test. Interpretation and Conclusions. This ELISA assay can be useful in the identification and classification of VWD patients in that it may provide a more accurate distinction between type 2 disease with abnormal VWF function and type 1 disease with a low plasma concentration of VWF.

Original languageEnglish
Pages (from-to)77-85
Number of pages9
JournalHaematologica
Volume89
Issue number1
Publication statusPublished - Jan 2004

Keywords

  • Diagnosis and classification
  • Ristocetin co-factor activity
  • Von Willebrand factor
  • Von Willebrand factor activity
  • Von Willebrand's disease

ASJC Scopus subject areas

  • Hematology

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