Hemostatic effect of a heat-treated factor VIII concentrate (Haemate P) in von Willebrand's disease

A heat-treated factor VIII (F VIII) concentrate (Haemate P) has been administered to patients with various types of von Willebrand's disease (vWD). The 4 activities of F VIII/vWF as well as change in the multimeric structure of vWF were then studied. In 4 patients with type I vWF who were given a Ristocetin cofactor (Rcof) dose of 42-78 U/kg, there was a clear reduction of the bleeding time and an increase of F VIII: C, F VIII: Ag, Rcof and vWF: Ag for several hours. The recovery of Rcof. after 1 h was 50-75%. Although the multimeric composition of vWF in these patients was similar to that of normal plasma, the density of each multimer band was very low. After infusion, however, the density of all multimer bands increased for several hours, to decrease again after 24 h. In 4 patients with type II A vWD who received a dose of Rcof of 55-76 U/kg, the 4 activities of F VIII/vWF increased similarly as was the case in type I. All patients had only 3-4 smaller multimer bands. New larger and intermediate multimers appeared for several hours after infusion of the preparation. Two patients with type III vWD who received doses of Rcof of 52 and 65 U/kg showed also a similar increase in the 4 activities of F VIII/vWF after infusion. All the multimers lacking in these patients appeared for several hours after infusion.     

Clinical effectiveness of desmopressin in a case of acquired von Willebrand's syndrome associated with benign monoclonal gammopathy

A case of acquired von Willebrand's syndrome (avWs) secondary to benign monoclonal gammopathy, is described, in which desmopressin (DDAVP) has proven effective repeatedly in preventing bleeding after tooth extraction. The laboratory pattern was similar to that of congenital type IA von Willebrand's disease. After DDAVP, prolonged bleeding time and factor VIII/von Willebrand factor activities were normalized. The disappearance rate of the elicited activities was similar to that observed in patients with congenital disease. This report adds to the scarce data concerning the haemostatic effectiveness of DDAVP in avWs and suggests that this agent might also be used in controlling or preventing bleeding in patients with the acquired disease, selected on the basis of their biological responsiveness to a test-infusion.     

Multimers of von Willebrand antigen in therapeutic factor VIII concentrates

By crossed immunoelectrophoresis (XIEP), the pattern of von Willebrand factor antigen (vWF:Ag) was investigated in six commercially available factor VIII (F VIII) concentrates and in normal human plasma. At least 5 subpopulations of vWF:Ag were recognized by XIEP in the therapeutic F VIII concentrates and in normal plasma. F VIII preparations high in ristocetin cofactor activity (vWF:RICof) and low in the ratio of vWF:Ag to vWF:RiCof were found to be similar in the multimeric structure of vWF:Ag to normal plasma. However, F VIII concentrates low in activity of vWF:RiCof and high in the ratio of vWF:Ag to vWF:RiCof were found to be deficient in the slowly migrating, high molecular weight multimers of vWF:Ag present in normal plasma.     

Prevalence of human immunodeficiency virus (HIV) infection among hemophiliacs in Fukuoka, Japan

To determine when the hemophiliacs in Fukuoka prefecture, Japan, first became positive for antibodies, we tested human immunodeficiency virus (HIV) antibodies on serum samples obtained from 1976-1987 stored at -30 C. Fifteen out of 64 hemophilia A patients (23.4%), five out of 11 hemophilia B patients (45.5%), but none of 17 patients with von Willebrand's disease (0%) were positive for HIV antibodies. In this series, two with hemophilia A became positive for HIV antibodies for the first time in 1983, and in 1984 another four with hemophilia A and one with hemophilia B became positive.     

Exercise-induced changes of Factor VIII complex in healthy subjects and in type-I diabetics: relation between growth hormone and Von Willebrand Factor increments

This work aims to study the exercise-induced changes of Factor VIII Complex both in healthy subjects and in type I diabetics without vascular complications, and to investigate the possible relations between growth hormone and Von Willebrand's Factor response to exercise. Results show that maximal exercise performed by cycle ergometer causes a significant increment of the procoagulant subunit (VIII:C) and of Von Willebrand Factor (VIII:RiCoF) both in healthy controls and in type I diabetics, whereas a slight increment of Factor VIII-Related antigen (VIIIR:Ag) is observed only in diabetics. The shape of the mean GH response to exercise parallels the one of Von Willebrand's Factor: however, the presence of VIII:RiCoF increments also in GH non-responders supports the conclusion that growth hormone is not the only factor involved in the regulation of Von Willebrand's Factor exercise-induced increase.     

The use of heat-treated Factor VIII-concentrates in von Willebrand's disease

In vitro investigations have demonstrated a high F VIII:Rcof potency and a high F VIII:Rcof/F VIII R:Ag ratio of two heat-treated F VIII concentrates. We therefore studied the in vivo effectiveness of these preparations (F VIII HSR, Behringwerke Marburg and F VIII HTR, Travenol) in five patients with von Willebrand's disease (vWd). In the steady state in vivo recoveries of F VIII:Rcof ranged from 73-153% after transfusion of F VIII HSR and from 11.5-17% after F VIII HTR respectively. The gain of F VIII-complex after F VIII HS was comparable to cryopecipitate (KryobulinR SP, Immuno AG Wien). All three products shortened the bleeding-time. Three of our five patients underwent surgery (Billroth I, papillotomy, laparatomy, open heart surgery) under F VIII HS cover without bleeding complications. The dose applied ranged from 20 to 40 U/kg at 8 or 12 h intervals for a period of approx. 14 days. Serum-transaminase elevations were observed in two of four patients after F VIII HT treatment. Although the risk of hepatitis of heat-treated F VIII concentrates remains to be determined, these products proved to be effective in vWd. The major advantages of these preparations are stability, rapid solubility, a low content of contaminating proteins, and a rapid, general availability.     

Desmopressin and bleeding time in patients with cirrhosis.

Desmopressin acetate 0.3 microgram/kg was given intravenously to nine patients with chronic liver disease and to a further six such patients in a double blind controlled study versus placebo. Desmopressin acetate significantly shortened the bleeding time compared with basal values in both groups and compared with placebo. There was also a significant decrease in partial thromboplastin time (but not prothrombin time) and significant increases in factor VIII and its components, von Willebrand factor and ristocetin cofactor activity, but not in factors VII, IX, X, XI, or XII. Increased fibrinolysis could be blocked by concomitant administration of tranexamic acid. No important side effects were seen. The multimer pattern of von Willebrand factor was studied for the first time in chronic liver disease. It was normal, but after administration of desmopressin acetate the percentage of multimers of higher molecular weight increased significantly. This may be an important mechanism in the shortening of the bleeding time in cirrhosis, as has been shown in uraemia and other conditions after administration of desmopressin acetate. Desmopressin acetate may be useful in correcting defects in primary haemostasis in chronic liver disease.     

Desmopressin decreases operative blood loss in spinal cord injury patients having flap reconstruction of pelvic pressure sores.

To test the effectiveness of desmopressin in decreasing operative blood loss in major flap reconstructions, 44 hemostatically normal patients with spinal cord injury and pelvic pressure sores participated in a randomized, prospective, double-blind clinical trial. Each patient received a single dose of desmopressin (0.3 micrograms/kg) or saline placebo intravenously at the initiation of a reconstructive surgical procedure. Preoperative and postoperative hemoglobin, hematocrit, von Willebrand factor, and factor VIII determinations and measurement of intraoperative blood loss and transfusions of packed red cells were recorded. Desmopressin-treated patients experienced a smaller decline in hemoglobin and hematocrit levels postoperatively. In those patients requiring major flap reconstructions, the use of desmopressin significantly decreased intraoperative blood loss and subsequent transfusion requirements. The levels of von Willebrand factor and factor VIII tended to be higher, although not significantly so, in subjects receiving desmopressin. No patient experienced an adverse reaction to the drug. We conclude that a single dose of desmopressin, given immediately preoperatively, is safe and effectively decreases blood loss and transfusion requirements in patients undergoing major flap reconstructive surgery.     

Immunologic dysfunction in patients with classic hemophilia receiving lyophilized factor VIII concentrates and cryoprecipitate.

The occurrence of the acquired immune deficiency syndrome (AIDS) in patients with hemophilia has suggested that an infectious agent transmitted through the frequent use of pooled blood products could be responsible. To determine if the amount or type of factor VIII preparation alters the risk of acquiring immune defects, three groups of asymptomatic heterosexual men were studied: 34 with severe classic hemophilia who were receiving lyophilized factor VIII concentrate, 10 with either mild classic hemophilia or moderately severe von Willebrand''s disease who were receiving cryoprecipitate and 22 normal men who served as controls. Anergy was noted in 68%, 57% and 5% respectively of the three groups. In comparison with the control group, the group treated with lyophilized factor VIII concentrate had a significantly decreased mean ratio of helper to suppressor T lymphocytes, poor responses of the lymphocytes to mitogens, high unstimulated background activity of these cells and significantly elevated serum IgG levels. Although some of the patients with classic hemophilia who were treated with cryoprecipitate were also anergic, they did not manifest these in-vitro abnormalities. The data indicate that a majority of apparently immunocompetent individuals with classic hemophilia show in-vivo and in-vitro evidence of impaired cellular immunity and may be at risk for the development of opportunistic infections and neoplasms.     

ATP-dependent dissociation of non-disulfide-linked aggregates of coagulation factor VIII is a rate-limiting step for secretion

Deficiency in coagulation factor VIII leads to the bleeding disorder hemophilia A. Previous studies demonstrated that factor VIII secretion is limited due to an ATP-requiring step early in the secretory pathway. In this report, we identified that this ATP-dependent rate-limiting step involves the dissociation of non-disulfide-linked aggregates within the endoplasmic reticulum (ER). In contrast to the numerous examples of interchain disulfide-linked aggregates, factor VIII is the first protein characterized to form non-disulfide-linked high molecular weight aggregates within the ER. Approximately a third of newly synthesized factor VIII was detected in high molecular weight aggregates. These aggregates disappeared over time as functional factor VIII appeared in the medium. The aggregated complexes did not require proteasomal degradation for clearance. Aggregate formation was enhanced by ATP depletion, and upon restoration of metabolic energy, these aggregates were dissociated and secreted. With the coexpression of von Willebrand factor (vWF), a small portion of vWF coaggregated with factor VIII. However, vWF dissociated from the aggregates more rapidly than factor VIII, supporting that these aggregates are dynamic. An increase in the factor VIII expression level elicited a corresponding increase in the fraction of factor VIII that was aggregated. In addition, a 110 amino acid sequence containing a hydrophobic beta-sheet within factor VIII was identified that may predispose factor VIII to aggregation. These data show that formation and ATP-dependent dissolution of nondisulfide-linked factor VIII aggregates is a dynamic, rate-limiting step during the folding process in the early secretory pathway. In summary, we have identified an unprecedented requirement for protein transport out of the ER that involves an ATP-dependent dissociation of non-disulfide-linked aggregates within the ER.     

Genetic and blood coagulation characterization of “Swedish” families with von Willebrand's disease types I and III: New aspects of heredity

Summary Twenty-five patients with von Willebrand's disease (vWD) type III were analysed with regard to blood coagulation variables and possible deletions. Nine of the probands and their families were further investigated with DNA linkage analyses. Different patterns of heredity can be suggested in our families with vWD type III, on the basis of blood coagulation analyses. The findings suggest homozygosity in five families and the possibility of compound heterozygosity or a new mutation in the proband in three families. The linkage analyses confirm the results of the coagulation analyses. The segregation of the von Willebrand factor (vWF) gene can be followed in the families, and carrier diagnosis can be made in several of the probands' relatives. The possibility of large deletions in the vWF gene of the probands and their parents was investigated with probes representing the whole vWF cDNA. No deletions were found.This study was approved by the Ethics Committee of the Karolinska Hospital (No. 84:1)     

Storage of factor VIII variants with impaired von Willebrand factor binding in Weibel-Palade bodies in endothelial cells

Background

Point mutations resulting in reduced factor VIII (FVIII) binding to von Willebrand factor (VWF) are an important cause of mild/moderate hemophilia A. Treatment includes desmopressin infusion, which concomitantly increases VWF and FVIII plasma levels, apparently from storage pools containing both proteins. The source of these VWF/FVIII co-storage pools and the mechanism of granule biogenesis are not fully understood.

Methodology/Principal Findings

We studied intracellular trafficking of FVIII variants implicated in mild/moderate hemophilia A together with VWF in HEK293 cells and primary endothelial cells. The role of VWF binding was addressed using FVIII variants displaying reduced VWF interaction. Binding studies using purified FVIII proteins revealed moderate (Arg2150His, Del2201, Pro2300Ser) to severe (Tyr1680Phe, Ser2119Tyr) VWF binding defects. Expression studies in HEK293 cells and primary endothelial cells revealed that all FVIII variants were present within VWF-containing organelles. Quantitative studies showed that the relative amount of FVIII storage was independent of various mutations. Substantial amounts of FVIII variants are co-stored in VWF-containing storage organelles, presumably by virtue of their ability to interact with VWF at low pH.

Conclusions

Our data suggest that the potential of FVIII co-storage with VWF is not affected in mild/moderate hemophilia A caused by reduced FVIII/VWF interaction in the circulation. These data support the hypothesis that Weibel-Palade bodies comprise the desmopressin-releasable FVIII storage pool in vivo.     

Increased factor VIII/vWf levels in patients with reduced platelet number

Factor VIII/von Willebrand factor (VIII/vWf) related properties were studied in twenty six patients with thrombocytopenia. Fifteen patients were affected by idiopathic thrombocytopenic purpura (ITP) and 11 patients by thrombocytopenia of a different nature or non-ITP (n-ITP). All patients showed an enhancement of platelet associated IgG (PAIgG). A significant increase of factor VIII ristocetin cofactor (VIII R: RCoF) and factor VIII related antigen (VIII R:Ag) was found in ITP patients while normal values were observed for factor VIII coagulant (VIII:C). All factor VIII/vWf components, on the contrary, were increased in n-ITP group with a prevalence of VIII R:RCoF as observed in ITP group even though with lower mean values. Multimeric analysis of VIII/vWf demonstrated a higher concentration of all multimeric components, with major representation of higher molecular weight multimers (HMWM) in patients of both groups. Two patients were studied before and after improvement in platelet count. A decrease of vWf related properties (VIII R:RCoF and VIII R:Ag) concomitant with the increase in platelet count was found. In n-ITP patients a statistical correlation between VIII R:RCoF and PAIgG was also observed while no correlation was found between other factor VIII/vWf components and PAIgG both in ITP and n-ITP patients.     

The effect of plasma von Willebrand factor on the binding of human factor VIII to thrombin-activated human platelets

The binding of 35S-labeled recombinant human Factor VIII to activated human platelets was studied in the presence and absence of exogenous plasma von Willebrand factor. In the absence of added von Willebrand Factor, platelets bound 210 molecules of Factor VIII/platelet when the unbound Factor VIII concentration was 2.0 nM (Kd = 2.9 nM). As the von Willebrand factor concentration was increased, the number of Factor VIII molecules bound/platelet decreased to 10 molecules of Factor VIII bound/platelet at 24 micrograms/ml of added vWF. Addition of an anti-vWF monoclonal antibody that inhibits the vWF-Factor VIII interaction attenuated the ability of vWF to inhibit binding of Factor VIII to platelets. In contrast, addition of a control anti-vWF antibody that does not block the vWF-Factor VIII interaction did not affect the ability of vWF to inhibit Factor VIII binding to platelets. From the vWF concentration dependence of inhibition of Factor VIII-platelet binding, a dissociation constant for the Factor VIII-vWF interaction was calculated (Kd = 0.44 nM). To further elucidate the role that vWF may play in preventing the interaction of Factor VIII with platelets, the platelet binding properties of a Factor VIII deletion mutant (90-73) which lacks the primary vWF-binding site was studied. The binding of this mutant was unaffected by added exogenous vWF. These observations demonstrate that Factor VIII can interact with platelets in a manner independent of vWF but that excess vWF in plasma can effectively compete with platelets for the binding of Factor VIII. In addition, since cleavage of Factor VIII by thrombin separates a vWF-binding domain from Factor VIIIa, we propose that activation of Factor VIII by thrombin may elicit release of activated Factor VIII from vWF and thereby make it fully available for platelet binding.     

Studies on factor XIII antigen in congenital factor XIII deficiency. A tentative classification of the disease in two groups.

Immunological and immunofluorescent studies carried out on plasma and platelets of three cases of congenital factor XIII deficiency are reported. Two of these patients were originally thought to have normal factor XIII subunit S and no subunit A. However, repeated assays carried out using different lots of antiserum showed that in reality the patients lacked both subunit S and subunit A. The false positive finding was due to the presence of a anti-factor VIII contaminant in the antiserum originally used. The third patient had a normal subunit S and no subunit A. No factor XIII antigen was found by the indirect immunofluorescent technique in normal, factor XIII deficiency and von Willebrand's disease platelets. On the contrary, by using the non-monospecific antiserum a fluorescent pattern similar to that observed by using an anti-factor VIII antiserum, had been noted. On the basis of the data presented in this paper a tentative classification of factor XIII deficiency in two groups is proposed: Type I is characterized by the lack of both factor XIII subunit S and A. Type II is characterized by a normal subunit S and no subunit A. The need for a re-evaluation of published case of factor XIII deficiency by means of monospecific antisera is indicated.     

The Influence of Helicobacter pylori Status on Circulating Levels of the Coagulation Factors Fibrinogen, von Willebrand Factor, Factor VII, and Factor VIII

Background. Helicobacter pylori (H. pylori) infection has been associated with an increased risk of developing ischemic heart disease (IHD). It has been suggested that a persisting low-grade acute phase response results from the chronic inflammation caused by H. pylori infection, which may give rise to increased circulating levels of certain coagulation factors.
Materials and Methods. One hundred three (53 male) nonconsecutive, randomly selected white subjects with symptoms of dyspepsia were recruited for study from an outpatient endoscopy clinic at Leeds General Infirmary. The presence of H. pylori was determined by histological and microbiological investigation, a rapid urease test, and a ¹³carbon urea breath test (¹³C-UBT). Fibrinogen was measured by the Clauss method, factor VIII:C (FVIII:C) and factor VII:C (FVII:C) were measured by clotting rate assays, and the von Willebrand factor (vWF) was determined by an enzyme-linked immunosorbent assay.
Results. No difference was found in levels of coagulation factors according to H. pylori status. Multiple regression models were used to account for the effect of covariates and H. pylori status on levels of FVII:C, FVIII:C, vWF, and fibrinogen, and again H. pylori status was not a significant determinant of levels of any of these coagulation factors. No difference occurred in full blood count, platelet count, white cell count, or plasma viscosity in individuals who were H. pylori -positive compared with those who were negative.
Conclusions. H. pylori infection is not associated with increased circulating levels of fibrinogen, FVII:C, vWF.Ag, or FVIII:C or hemorrheology in this patient group.     

Biochemical and molecular characterization of von Willebrand disease type 2N in a pregnant patient who gave birth under analgesia with remifentanil

von Willebrand 's disease (vWD) is the commonest inherited bleeding disorder. Although in literature there are some cases reported of epidural analgesia for labor pain in pregnancies with Von Willebrand's disease, the technique is not free from risk of neurolocal complications. Authors reported a case of spontaneous labor in a pregnant woman with type II vWD, delivered under local analgesia administered through a continuous intravenous infusion of remifentanil integrated by boli. A 34-year-old woman at the 39th week of her second pregnancy was admitted for an active labor of a single fetus in cephalic presentation. The patient had been diagnosed with type II vWD by a hematologist during her first pregnancy. The patient coagulation panel was as follows: a reduction of VIIIth factor concentration (21 percent); a normal value of vWD functional assay; an increase of vWf:Ag (antigen) and a reduction of XIth factor. During labor she was put on remifentanil in PCA (patient controlled analgesia), administered with slow boli followed by continuous infusions at increasing doses. The woman delivered a female fetus weighing 3,550 g, in vertex presentation, in left anterior occipital position, with an A.P.G.A.R. of 8 at the first minute and 9 at the fifth minute. The total duration of labor was 3 hours and 10 minutes. The patient was satisfied with analgesia in labor. The bleeding during and after delivery was regular. In the authors ' opinion, it is important to know that an alternative to epidural analgesia can be used in order to avoid the risk of neurological complications in labor pain for patients with type II Von Willebrand's disease.     

A major factor VIII binding domain resides within the amino-terminal 272 amino acid residues of von Willebrand factor

We have identified a Factor VIII (FVIII) binding domain residing within the amino-terminal 272 amino acid residues of the mature von Willebrand Factor (vWF) subunit. Two-dimensional crossed immunoelectrophoresis showed direct binding of purified human FVIII to purified human vWF. After proteolytic digestion of vWF with Staphylococcus aureus V8 protease (SP), FVIII binding was seen only with the amino-terminal SP fragment III and not with the carboxyl-terminal SP fragment II. A monoclonal anti-vWF antibody (C3) partially blocked FVIII binding to vWF and SP fragment III. FVIII also bound to vWF which had been adsorbed to polystyrene beads. This binding was inhibited in a dose-dependent manner by whole vWF, SP fragment III, and by monoclonal antibody C3. Binding could not be inhibited by SP fragment I, which contains the middle portion of the vWF molecule, or by reduced and alkylated whole vWF. SP fragment II caused only minimal inhibition. Trypsin cleavage of SP fragment III produced a monomeric 35-kDa fragment containing the amino-terminal 272 amino acid residues of vWF. This fragment reacted with monoclonal antibody C3 and inhibited the binding of FVIII to vWF in a dose-dependent manner. These studies demonstrate that a major FVIII binding site resides within the amino-terminal 272 amino acid residues of vWF.     

The role of von Willebrand factor multimers and propeptide cleavage in binding and stabilization of factor VIII

von Willebrand factor (vWF) is a multimeric glycoprotein that promotes platelet aggregation and stabilizes coagulation factor VIII in the plasma. vWF is also required for the stable accumulation of recombinant factor VIII secreted from cells in a heterologous expression system. In this report, we show that vWF can promote the in vitro reconstitution of factor VIII activity from dissociated heavy and light chains of factor VIII, suggesting that vWF may act to promote stable assembly of factor VIII subunits at the site of secretion. The structural requirements for vWF propeptide cleavage and for vWF multimerization in its binding and stabilization of factor VIII was examined using specifically altered recombinant vWF. The mutant vWF molecules were also assayed for their function in ristocetin-induced platelet agglutination mediated through the platelet receptor GPIb. Deletion of the vWF propeptide produced a dimeric vWF molecule that failed to mediate platelet agglutination, suggesting that multimerization is required for vWF to attain functional GPIb binding. This mature dimeric form of vWF, however, was fully capable of binding to and supporting stable secretion of factor VIII. A vWF mutant with an altered propeptide cleavage site formed large multimers of uncleaved pro-vWF that functioned in platelet agglutination. However, this noncleavage mutant neither bound to or supported stable accumulation of factor VIII. Analysis of the vWF propeptide, expressed independently, demonstrated that it could not bind factor VIII or stabilize its secretion. These results show that the dimeric mature vWF subunit is sufficient to bind and stabilize factor VIII and that the presence of uncleaved vWF propeptide inhibits both factor VIII binding and stabilization.     

Stoichiometry of the porcine factor VIII-von Willebrand factor association

Factor VIII and von Willebrand factor (vWF) are glycoproteins that form a tightly bound complex in plasma. The interaction of porcine factor VIII with porcine vWF was studied by analytical velocity sedimentation. A single approximately 240-kDa species of factor VIII was isolated for use in the analysis. In contrast, when analyzed by agarose/sodium dodecyl sulfate-polyacrylamide gel electrophoresis, vWF consisted of a population of greater than 10 multimers derived from a 270-kDa monomer. A single boundary (So20,w = 7.2 S) was observed during velocity sedimentation of factor VIII at 260,000 x g. A single boundary also was observed for vWF (weight-average So20,w = 21 S) at 42,000 x g. Under condition of excess factor VIII, the weight-average So20,w of the factor VIII-vWF complex was 40 S at 42,000 x g. At 260,000 x g, the factor VIII-vWF complex had sedimented completely, leaving only free factor VIII. The height of the plateau region of the factor VIII sedimentation velocity curve at 260,000 x g was studied as a function of several starting concentrations of vWF. The experiments were done under conditions in which the effect of radial dilution was negligible so that the plateau height was a measure of the concentration of free factor VIII. The plateau height decreased linearly as the concentration of vWF was increased, indicating that the association was essentially irreversible under the conditions used. A stoichiometry of 1.2 vWF monomers/factor VIII molecule was calculated from the slope of the line. Assuming one factor VIII-binding site/vWF monomer, these results indicate that all factor VIII-binding sites are accessible in the vWF multimer.