The Application of a Monoclonal Antibody to Factor VIII Related Antigen (VIIIRAg) in Immunoradiometric Assays for Factor VIII

1985 ◽  
Vol 53 (01) ◽  
pp. 143-147 ◽  
Author(s):  
J E Thomas ◽  
I R Peake ◽  
J C Giddings ◽  
A N Welch ◽  
A L Bloom
Keyword(s):  
Monoclonal Antibody ◽  
Factor Viii ◽  
Solid Phase ◽  
Polyclonal Antibodies ◽  
Inhibitory Effect ◽  
Immunoradiometric Assay ◽  
Strong Inhibitory Effect ◽  
Cofactor Activity ◽  
Ristocetin Cofactor ◽  
Ristocetin Cofactor Activity

SummaryA two site solid phase immunoradiometric assay (IRMA) for VIIIRAg has been developed using a monoclonal antibody as both the solid phase ligand and the radiolabelled antibody. A range of normal plasmas and von Willebrand’s disease (vWd) plasmas has been assayed for VIIIRAg by this method and compared with VIIIRAg values measured by an IRMA using polyclonal antibodies and by immunoelectrophoresis and with ristocetin cofactor activity (VIIIRiCoF). It was found that the monoclonal IRMA correlated well with the polyclonal IRMA and the immunoelectrophoretic assay, but the correlation with the VIIIRiCoF assay was relatively poor, in spite of the strong inhibitory effect of the antibody on VIIIRiCoF activity.

scholarly journals Selective absence of large forms of factor VIII/von Willebrand factor in acquired von Willebrand's syndrome. Response to transfusion

Blood ◽  
1979 ◽  
Vol 54 (3) ◽  
pp. 600-606 ◽  
Author(s):  
D Meyer ◽  
D Frommel ◽  
MJ Larrieu ◽  
TS Zimmerman
Keyword(s):  
Factor Viii ◽  
Von Willebrand Factor ◽  
Von Willebrand Disease ◽  
Procoagulant Activity ◽  
Factor Viii Related Antigen ◽  
Cofactor Activity ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Ristocetin Cofactor ◽  
Ristocetin Cofactor Activity

Abstract A previously healthy elderly man with mucocutaneous bleeding was found to have a benign monoclonal IgG gammapathy associated with criteria for severe von Willebrand disease (Factor VIII procoagulant activity, Factor-VIII-related antigen, and ristocetin cofactor activity, less than 10% of normal). Associated qualitative abnormalities of factor VIII/von Willebrand factor were demonstrated by radiocrossed immunoelectrophoresis and immunoradiometric assay. The late clinical onset and negative family history are in favor of an acquired form of vWD. The monoclonal gammapathy and abnormalities of factor VIII/von Willebrand factor have been stable over a 10-yr period. No inhibitor to Factor VIII procoagulant activity, ristocetin cofactor activity, or Factor-VIII-related antigen could be demonstrated. Following transfusion of cryoprecipitate (with a normal cross immunoelectrophoretic pattern), there was a rapid removal of the large forms of Factor.-VIII-related antigen, paralleled by a decay of ristocetin cofactor activity. The transfusion study of this patient with acquired von Willebrand disease type II (variant of von Willebrand disease) serves to emphasize the relationship between polydispersity of Factor VIII/von Willebrand Factor and functional heterogeneity.

scholarly journals Variant von Willebrand's disease and pregnancy

Blood ◽  
1981 ◽  
Vol 58 (5) ◽  
pp. 873-879 ◽  
Author(s):  
W Hanna ◽  
D McCarroll ◽  
T McDonald ◽  
P Painter ◽  
J Tuller ◽  
...  
Keyword(s):  
Factor Viii ◽  
Half Life ◽  
Clinical Course ◽  
Procoagulant Activity ◽  
Von Willebrand's Disease ◽  
Factor Viii Related Antigen ◽  
Coagulation Profile ◽  
Cofactor Activity ◽  
Ristocetin Cofactor ◽  
Ristocetin Cofactor Activity

Abstract The clinical course and coagulation profile of a pregnant patient with variant von Willebrand's disease were followed from the second trimester through puerperium. The clinical course was characterized by a normal delivery and absence of abnormal bleeding or need for replacement therapy. The coagulation profile demonstrated an increase in factor VIII procoagulant activity, factor-VIII-related antigen, and platelet aggregation activity in response to ristocetin prior to delivery. Postpartum, these factors decreased to prepregnancy values with distinctly different patterns. Factor VIII procoagulant activity continued to rise for 5 days after delivery and then decreased with a half-life of approximately 6 days. Factor-VIII-related antigen began to decrease just prior to delivery, displaying a half-life or approximately 6 days. Ristocetin cofactor activity, however, dropped immediately postpartum and displayed a half-life of approximately 6 hr. The ristocetin cofactor activity was associated with factor-VIII- related antigen, which displayed a significantly smaller molecular weight than does normal factor-VIII-related antigen. Larger aggregates of factor-VIII-related antigen. Larger aggregates of factor-VIII- related antigen did not appear during the pregnancy, and ristocetin cofactor activity could not be demonstrated in fragments of less than 0,8 x 10(6).

Von Willebrand Activity of Low Molecular Weight Human Factor VIII Increases by Binding to Gold Granules

1981 ◽  
Vol 45 (03) ◽  
pp. 242-246 ◽  
Author(s):  
Miha Furlan ◽  
Beat A Perret ◽  
Eugene A Beck
Keyword(s):  
Molecular Weight ◽  
Factor Viii ◽  
Human Factor ◽  
Low Molecular Weight ◽  
Human Factor Viii ◽  
Large Factor ◽  
Cofactor Activity ◽  
Von Willebrand ◽  
Ristocetin Cofactor ◽  
Ristocetin Cofactor Activity

SummaryHuman factor VIII/von Willebrand protein is a population of multimers which vary in size but contain apparently identical subunits. Large-molecular-weight forms possess higher ristocetin cofactor/von Willebrand activity than the native smaller oligomers. Disulfide reduction of large factor VIII multimers results in progressively decreasing molecular size and a loss of ristocetin cofactor activity. Small molecular forms of factor VIII were adsorbed onto gold granules (average diameter 20-30 nm) and thereby increased their ristocetin cofactor activity. The amount of adsorbed material and the extent of activation were dependent on the pH of the colloid suspension. The maximum recovery of von Willebrand activity was observed at pH 4.75. Aggregation of fixed human platelets by factor VIII-coated gold particles was dependent on ristocetin concentration and was not competitively inhibited by unbound low-molecular-weight factor VIII. These results suggest that the subunits of the native small factor VIII species possess potential binding affinity for platelet receptors, which is manifested following formation of large factor VIII polymers. We conclude that an optimal size of remarkably high molecular weight is required for efficient aggregation of platelets by factor VIII as occurs during the primary phase of hemostasis.

A Rapid One-Step Immunoradiometric Assay for Factor VIII-Procoagulant Antigen Utilizing Monoclonal Antibodies

1983 ◽  
Vol 50 (04) ◽  
pp. 860-863 ◽  
Author(s):  
H V Stel ◽  
E C I Veerman ◽  
J G Huisman ◽  
M C Janssen ◽  
J A van Mourik
Keyword(s):  
Monoclonal Antibody ◽  
Monoclonal Antibodies ◽  
Factor Viii ◽  
Lower Limit ◽  
Solid Phase ◽  
Immunoradiometric Assay ◽  
Step Procedure ◽  
One Step

SummaryA two-site immunoradiometric assay for factor VIII-procoagulant antigen (VIIICAg) that relies completely on monoclonal antibodies has been developed. By selecting an appropriate combination of these antibodies, it was possible to develop an assay in which the radiolabelled monoclonal antibody did not inhibit the binding of antigen to the solid-phase monoclonal antibodies. Thus, the entire test could be carried out as a one-step procedure. With this one-step assay, an amount of 0.0025 U VIIICAg/ml plasma could be detected after 4 hr of incubation, whereas 18 hr of incubation resulted in a lower limit of sensitivity of 0.0005 U VIIICAg/ml. The use of a one-step assay provides a significant advantage over the conventional two-step assay by simplifying, shortening and rendering the performance of the assay more convenient.

scholarly journals Variant von Willebrand's disease and pregnancy

Blood ◽  
1981 ◽  
Vol 58 (5) ◽  
pp. 873-879
Author(s):  
W Hanna ◽  
D McCarroll ◽  
T McDonald ◽  
P Painter ◽  
J Tuller ◽  
...  
Keyword(s):  
Factor Viii ◽  
Half Life ◽  
Clinical Course ◽  
Procoagulant Activity ◽  
Von Willebrand's Disease ◽  
Factor Viii Related Antigen ◽  
Coagulation Profile ◽  
Cofactor Activity ◽  
Ristocetin Cofactor ◽  
Ristocetin Cofactor Activity

The clinical course and coagulation profile of a pregnant patient with variant von Willebrand's disease were followed from the second trimester through puerperium. The clinical course was characterized by a normal delivery and absence of abnormal bleeding or need for replacement therapy. The coagulation profile demonstrated an increase in factor VIII procoagulant activity, factor-VIII-related antigen, and platelet aggregation activity in response to ristocetin prior to delivery. Postpartum, these factors decreased to prepregnancy values with distinctly different patterns. Factor VIII procoagulant activity continued to rise for 5 days after delivery and then decreased with a half-life of approximately 6 days. Factor-VIII-related antigen began to decrease just prior to delivery, displaying a half-life or approximately 6 days. Ristocetin cofactor activity, however, dropped immediately postpartum and displayed a half-life of approximately 6 hr. The ristocetin cofactor activity was associated with factor-VIII- related antigen, which displayed a significantly smaller molecular weight than does normal factor-VIII-related antigen. Larger aggregates of factor-VIII-related antigen. Larger aggregates of factor-VIII- related antigen did not appear during the pregnancy, and ristocetin cofactor activity could not be demonstrated in fragments of less than 0,8 x 10(6).

Standards for Assay of von Willebrand Factor Concentrates: A Collaborative Study

1993 ◽  
Vol 70 (02) ◽  
pp. 351-356 ◽  
Author(s):  
W A Fricke ◽  
M A Lamb ◽  
S C Rastogi
Keyword(s):  
Factor Viii ◽  
Von Willebrand Factor ◽  
Collaborative Study ◽  
Von Willebrand Factor Antigen ◽  
Cofactor Activity ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Factor Antigen ◽  
Ristocetin Cofactor ◽  
Ristocetin Cofactor Activity

SummaryA multilaboratory collaborative study was undertaken to assess the feasibility of using a plasma standard for expressing the results of assays for the von Willebrand factor content of von Willebrand factor concentrates and of factor VIII concentrates. Thirteen laboratories tested six concentrates for von Willebrand factor antigen, ristocetin cofactor activity, and multimer content using the World Health Organization plasma standard for factor VIII/von Willebrand factor, 87/718, as a standard. Only a few assays were invalid because of nonparallelism or nonlinearity. Significant interlaboratory and interassay differences were found for both von Willebrand factor antigen and ristocetin cofactor activity. There was generally good agreement between the laboratories with respect to the multimer content in the preparations. With respect to assay validity, a plasma standard could be suitable for assaying concentrated preparations of von Willebrand factor.

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