Antibody to human factor VIII/von Willebrand factor inhibits collagen-induced platelet aggregation and release

The present studies were undertaken to determine whether factor VIII/von Willebrand factor (vWF) present in the vessel wall (in addition to that in plasma) may mediate the attachment of platelets to subendothelium. Subendothelium from everted rabbit aorta was exposed to human citrated blood flowing through an annular perfusion chamber at 40 mL/min (wall shear rate of 2,600 s-1 for five minutes). The vessel segments were incubated at 37 degrees C for one hour with various dilutions of either goat-anti-rabbit factor VIII/vWF serum or an IgG fraction prepared from the serum. Control segments were incubated with serum or IgG from a nonimmunized goat. Values of platelet contact (C), platelet adhesion (C + S), and thrombus formation (T) on the subendothelium were evaluated by a morphometric technique. Compared with vessels incubated with fractions prepared from a normal goat, a significant decrease in platelet adhesion (C + S), ranging from 45% to 65%, was observed on vessels incubated with various dilutions (1:5 to 1:50) of either serum or IgG fractions of goat-anti-rabbit factor VIII/vWF. A similar decrease in platelet adhesion was observed with vessels incubated with an F(ab')2 fragment against rabbit factor VIII/vWF prepared in the goat. When goat-anti-rabbit factor VIII/vWF IgG was added to rabbit blood (1:75 dilution), platelet adhesion was reduced to the same extent (65%) on normal rabbit vessels and on vessels pre-incubated with goat-anti-rabbit factor VIII/vWF. Immunofluorescence studies revealed the presence of rabbit factor VIII/vWF in the subendothelium of rabbit aorta and the continued binding of the goat-anti-factor VIII/vWF antibodies on subendothelium during the perfusion studies. No uptake of human factor VIII/vWF on the rabbit subendothelium was observed by this immunologic technique; human factor VIII/vWF was found to be entirely associated with the attached human platelets. Thus, factor VIII/vWF in the vessel wall may mediate platelet attachment to subendothelium in a manner similar to that of plasma factor VIII/vWF.

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Antihemophilic Factor/von Willebrand Factor Complex (Human) (Factor VIII Complex)

Pediatric Injectable Drugs ◽

10.37573/9781585285402.026 ◽

2018 ◽

pp. 90-95

Keyword(s):

Factor Viii ◽

Von Willebrand Factor ◽

Human Factor ◽

Human Factor Viii ◽

Von Willebrand ◽

Willebrand Factor ◽

Antihemophilic Factor

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Proteolytic activity of .alpha.2-macroglobulin-enzyme complexes toward human factor VIII/von Willebrand factor

Biochemistry ◽

10.1021/bi00275a018 ◽

1983 ◽

Vol 22 (6) ◽

pp. 1437-1444 ◽

Cited By ~ 9

Author(s):

Mary Ellen P. Switzer ◽

Helen J. Gordon ◽

Patrick A. McKee

Keyword(s):

Factor Viii ◽

Proteolytic Activity ◽

Von Willebrand Factor ◽

Human Factor ◽

Human Factor Viii ◽

Von Willebrand ◽

Willebrand Factor ◽

Enzyme Complexes

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von Willebrand Factor Activity in Plasmin Digests of Factor VIII

10.1055/s-0039-1680509 ◽

1977 ◽

Author(s):

J. A. Guisasola ◽

C. Cockburn ◽

R. M. Hardisty

Keyword(s):

Factor Viii ◽

Von Willebrand Factor ◽

Human Factor ◽

Factor Activity ◽

Group Iii ◽

Molecular Weights ◽

Human Factor Viii ◽

Group Ii ◽

Von Willebrand ◽

Willebrand Factor

Purified human factor VIII was incubated for up to 24 hours with plasmin, and the activity of the breakdown products studied at intervals. Factor VIII coagulant activity was lost within the first hour, but von Willebrand factor activity (FVIIIR:WF) was retained for two hours, and then declined slowly during the subsequent incubation. Analysis of the 24-hour breakdown products by immuno-electrophoresis, sepharose 4B chromatography and SDS Polyacrylamide electrophoresis revealed three main groups of fragments recognised by rabbit anti-human factor VIII anti-serum, and having molecular weights in the following ranges: Group 1 300,000=500,000; Group II, 150–200,000; Group III, 100,000. FVIIIR:WF activity, which was found only in Group II, appeared to be associated with glycopeptide(s) of up to 155,000 daltons.

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