A rapid assay for ristocetin cofactor activity using an automated coagulometer (ACL 9000)

Lattuada, A; Preda, L.; Sacchi, Elisabetta; Gallo, Luciana; Federici, Augusto B.; Rossi, Edoardo

doi:10.1097/00001721-200408000-00011

Cited by 28 publications

(31 citation statements)

References 18 publications

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“…Monoclonal antibody-based ELISA, 3,4 Elisa-based VWF:RCo, 5,6 rapid assays for VWF:RCo using coagulometers, 7 and assays measuring the binding of VWF to collagen. 8 The aim of this study was to evaluate the novel fully automated HemosIL™VWF Activity assay on the ACL-Futura automated coagulometer (Instrumentation Laboratory) as a potential screening test for the diagnosis of VWD.…”

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confidence: 99%

Evaluation of a new turbidimetric assay for von Willebrand factor activity useful in the general screening of von Willebrand disease

Piñol¹,

Sales²,

Costa³

et al. 2007

Haematologica

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We evaluated a new assay (HemosIL™VWF Activity on ACL-Futura) in the screening of VWD. Samples from healthy donors and previously diagnosed VWD patients were blindly analyzed by this new activity assay and standard VWF:RCo. Results agreed and both assays showed a similar sensitivity for the screening of VWD. Haematologica 2007; 92:5: 712-713 Von Willebrand disease (VWD), the most frequent inherited bleeding disorder, is caused by a deficiency and/or abnormality of the von Willebrand factor (VWF).1,2 The revised classification of VWD identifies two major categories, characterized by quantitative (types 1 and 3) or qualitative (type 2) VWF defects.2 The most common test of VWF activity, the assay of VWF:RCo together with VWF:Ag is traditionally considered the first step in the diagnosis of VWD, with the VWF:RCo/Ag ratio being recommended to discriminate type 1 from type 2A, 2B and 2M VWD.1,2 Given the complexities of the aggregometric test, several alternative laboratory methods have been proposed to measure VWF activity. Monoclonal antibody-based ELISA, 3,4Elisa-based VWF:RCo, 5,6 rapid assays for VWF:RCo using coagulometers, 7 and assays measuring the binding of VWF to collagen.8 The aim of this study was to evaluate the novel fully automated HemosIL™VWF Activity assay on the ACL-Futura automated coagulometer (Instrumentation Laboratory) as a potential screening test for the diagnosis of VWD.9,10 The assay uses latex sensitized with monoclonal antibodies (RFF VIII:R/1) 3 directed against the platelet binding site of VWF (GPIb receptor). The activity of VWF is determined by measuring the increase of turbidity produced by the agglutination of the latex particles as a consequence of the interaction between the GPIb receptor of VWF and the monoclonal antibodies. The lower limit of linearity has been reported at 12.5IU/dL. 9 A set of 57 normal controls and 70 VWD patients from two Hemophilia Centers were blindly analyzed in the R&D laboratory of Biokit with HemosIL™VWF:Ag, HemosIL™VWF Activity and VWF:RCo (Dade Behring) performed on an optical aggregometer. All methods were used to analyze samples which were then classified as normal or VWD type 1, 2, or 3 using the same criteria in both activity assays. The cut-off declared by the HemosIL based on ABO group was used to define normality or VWD, and the Activity/Antigen (Act/Ag) ratio was used to define quantitative (type 1) or qualitative (type 2) VWD using 0.7 as cut-off.1 Sample values below detectability were classified as type 3.After classification and database lock, blindness was disclosed by the two Hemophilia Centers where the patient samples were classified according to the clinical and laboratory findings. Table 1 shows the mean VWF concentration in IU/dL±SD (standard deviation) obtained for each assay. The first column shows the Classification according to the Haemophilia Centers. Nine samples from the Vicenza group which correspond to type 1 according to the last classification scheme, 2 are shown separately. The last columns show the mean Act/Ag ratio...

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confidence: 99%

Evaluation of a new turbidimetric assay for von Willebrand factor activity useful in the general screening of von Willebrand disease

Piñol¹,

Sales²,

Costa³

et al. 2007

Haematologica

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“…The assay is available in 2 versions based on turbidimetric or chemiluminescence detection; both systems are precise and suitable for VWD diagnosis. [41][42][43][44] More recently, automatic VWF:GPIb-binding assays independent of ristocetin have been developed and introduced into general use with promising results. [45][46] …”

Section: Additional Automatic and Novel Assays For Phenotypic Diagnmentioning

confidence: 99%

Clinical and laboratory diagnosis of VWD

Federici

2014

Hematology

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VWD is the most common inherited bleeding disorder and is due to a deficiency and/or abnormality of VWF. VWD is inherited in an autosomal-dominant or autosomal-recessive pattern, but women are apparently more symptomatic. Three main criteria are required for correct diagnoses of VWD: (1) positive bleeding history since childhood, (2) reduced VWF activity in plasma, and (3) history of bleeding in the family. The bleeding score, together with baseline VWF levels and family history, have been proposed as more evidence-based criteria for VWD. Measurements of a reduced VWF activity in plasma are essential for the diagnosis of VWD; assays for the evaluation of the interactions between VWF and platelet glycoprotein Ib receptor with or without ristocetin, as well as VWF collagen binding, are currently in use. However, other tests such as VWF antigen, factor VIII, ristocetin-induced platelet agglutination, multimeric analysis, VWF propeptide, VWF/FVIII binding assay, and assessment of biological response to desmopressin are necessary to characterize VWD types. Levels of VWF activities Ͻ30 U/dL have been associated with a bleeding phenotype and the presence of mutations in the VWF gene. Learning Objectives• To identify patients at risk for VWD according to their history of bleeding using a specific questionnaire to calculate BS • To use appropriate laboratory tests to classify VWD patients • To predict the bleeding phenotype of VWD and the need for replacement therapy using BS and baseline VWF levels

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“…Historically, VWF:RCo was first utilized as an agglutination assay primarily in platelet aggregometers or using a manual visual slide agglutination procedure; both of these methods are laborious. VWF:RCo by platelet agglutination has also been successfully automated on many modern haemostasis analysers, including the Siemen's BCS, IL ACL instrumentation, Stago STAR and most recently the Sysmex CA-2000i/CA2100i instruments [41][42][43][44][45][46][47][48]. Methods for VWF:RCo based on flow cytometry have also been described [49,50], as have ELISA-based methods [51][52][53].…”

Section: Technical Considerations Strengths and Limitations Of Diffementioning

confidence: 99%

Diagnosis and classification of von Willebrand disease

Favaloro

2011

Blood Coagulation & Fibrinolysis

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von Willebrand disease (VWD) is considered to be the most common inherited bleeding disorder. VWD is diagnosed following a clinical and physical review, with personal and familial evidence of (primarily mucocutaneous) bleeding, and confirmed by laboratory testing. The latter typically entails initial plasma testing of factor VIII coagulant, von Willebrand factor (VWF) protein ('antigen') and VWF function which has classically been assessed using the ristocetin cofactor (VWF:RCo) assay. More recent attention has focussed on other functional VWF assays, such as collagen binding and so-called 'VWF activity' assays, as possible replacements to the VWF:RCo, or as supplementary tests of VWF 'function'. Additional laboratory testing can comprise a battery of confirmatory and VWD-type assisting assays, including VWF:multimer and von Willebrand factor VIII binding. This review aims to update knowledge of current VWD diagnostics with a particular emphasis on 'functional' VWF assays.

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A rapid assay for ristocetin cofactor activity using an automated coagulometer (ACL 9000)

Cited by 28 publications

References 18 publications

Evaluation of a new turbidimetric assay for von Willebrand factor activity useful in the general screening of von Willebrand disease

Evaluation of a new turbidimetric assay for von Willebrand factor activity useful in the general screening of von Willebrand disease

Clinical and laboratory diagnosis of VWD

Diagnosis and classification of von Willebrand disease

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