Stability of porcine factor VIII

Fass, David N.; Bowie, E. J. W.; Owen, Charles A.; Mann, Kenneth G.

doi:10.1016/0049-3848(75)90016-x

Cited by 12 publications

(5 citation statements)

References 4 publications

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“…The in vivo half life of FVIII is dependent upon the presence and concentration of VWF and is as short as 1 hour in the absence of this carrier protein [14, 15]. However, in the APTT clotting assay, VWF acts as an inhibitor of FVIIIc and becomes a confounder in this FVIII activity-based assay [4, 16].…”

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confidence: 99%

The “normal” factor VIII concentration in plasma

Butenas

Parhami-Seren

Undas

et al. 2010

Thrombosis Research

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Introduction The quantitation of factor (F)VIII by activity-based assays is influenced by the method, procedure, the quality and properties of reagents used and concentrations of other plasma proteins, including von Willebrand factor (VWF). Objective To compare FVIII concentrations measured by activity-based assays with those obtained by an immunoassay and to establish the influence of plasma dilution on the FVIII clotting activity (FVIIIc). Methods The APTT, a chromogenic assay (Coatest) and two in-house immunoassays were used. Albumin-free recombinant FVIII was used as the calibrator in all assays. Results For a group of 44 healthy individuals (HI), the mean value observed for FVIII antigen (FVIIIag; 1.22±0.56 nM; S.D.) is substantially higher than that for FVIIIc (0.65±0.29 nM) and the chromogenic assay (FVIIIch; 0.50±0.23 nM). A positive correlation between FVIIIag and VWFag with R2=0.20 was observed. Since plasma VWF has an inhibitory effect on FVIIIc, we evaluated the influence of plasma dilutions on FVIIIc in HI (n=105). At a 4-fold dilution, estimates of FVIIIc by clotting assay were much lower than FVIIIag (0.77±0.31 vs. 1.14±0.48 nM). At 10- and 25-fold dilutions, the estimated FVIIIc increased to 0.87±0.36 and 0.94±0.44 nM, respectively. Conclusions 1) In plasma, FVIIIag is higher than FVIIIc and FVIIIch; and 2) Real FVIII concentrations in plasma can be estimated by measuring FVIIIag.

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confidence: 99%

The “normal” factor VIII concentration in plasma

Butenas

Parhami-Seren

Undas

et al. 2010

Thrombosis Research

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“…In support of this concept, it has been shown that plasma vWF is required for a normal circulating half-life for factor VIII (56) and that vWf-free recombinant factor VIII associates with vWF after infusion (57). In addition to this effect on the state of factor VIII in the circulation, vWF also directly stabilized factor VIII (58).…”

Section: Influence Of Von Willebrand Factor On Factor VIII Activitymentioning

confidence: 93%

Issues with the Assay of Factor VIII Activity in Plasma and Factor VIII Concentrates

Lundblad¹,

Kingdon²,

Mann³

et al. 2000

Thromb Haemost

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SummaryA review of the literature suggests that assays accurate for the determination of factor VIII in plasma samples may not necessarily retain this accuracy when used for the determination of factor VIII in high-purity factor VIII concentrates such as Hemofil ® M. Review of assay data suggests that it is imperative to obtain maximal activation of the factor VIII in the sample with thrombin when using an assay system of isolated coagulation factors such as the two-stage assay or the various chromogenic substrate assays. Based on a combination of ease and reproducibility of performance and correlation of in vivo and in vitro measurements, it is recommended that the one-stage activated partial thromboplastin time performed with plasma from an individual with severe hemophilia A be used for the measurement of factor VIII potency. Chromogenic substrate assays can be used if care is taken to assure optimal activation of factor VIII by thrombin in the assay and the presence of sufficient factor IXa, phospholipid and calcium ions to stabilize factor Villa during the assay process.

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“…My committee had no objection to leaving it in my dissertation, but I regret not standing our ground on that one. The issue had been resolved more or less conclusively by 1982 or so, first through observations by Fass et al [25] and later by Weiss et al [26] that FVIIIc is stabilized in vitro by association with VWF. The defining experiments came with the transfusion of FVIIIc into humans with VWD.…”

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confidence: 99%

“…The issue had been resolved more or less conclusively by 1982 or so, first through observations by Fass et al . [25] and later by Weiss et al . [26] that FVIIIc is stabilized in vitro by association with VWF.…”

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Big piece, little piece or: Yes, factor VIII is a protein

Owen

2005

Journal of Thrombosis and Haemostasis

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Stability of porcine factor VIII

Cited by 12 publications

References 4 publications

The “normal” factor VIII concentration in plasma

The “normal” factor VIII concentration in plasma

Issues with the Assay of Factor VIII Activity in Plasma and Factor VIII Concentrates

Big piece, little piece or: Yes, factor VIII is a protein

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