Theodore S. Zimmerman

Immunologic differentiation of classic hemophilia (factor VIII deficiency) and von Willebrand's disease: With observations on combined deficiencies of antihemophilic factor and proaccelerin (factor V) and on an acquired circulating anticoagulant against antihemophilic factor

Heterologous antiserum was prepared in rabbits against highly purified human antihemophilic factor (AHF, factor VIII). This antiserum blocked the clot-promoting properties of AHF and, when suitably absorbed, formed a single precipitin line against AHF upon immunoelectrophoresis. Material antigenically similar to normal AHF was detected in normal amounts in plasma concentrates in each of 22 patients with classic hemophilia, in a patient with an acquired circulating anticoagulant against AHF, and in a patient with deficiencies both of AHF and proaccelerin (factor V). AHF-like antigen was present in normal human serum. In contrast, material antigenically related to AHF was found in decreased amounts in the concentrates prepared from the plasma of 11 patients with von Willebrands disease. The experiments described suggest that von Willebrands disease is a disorder in which a true deficiency of AHF exists. Whether the AHF-like material found in classic hemophilia is nonfunctional through a defect in structure or through the intervention of an inhibitor has not been shown.

Deamino-8-D-arginine vasopressin shortens the bleeding time in uremia

In a randomized double-blind cross-over trial we gave either 1-deamino-8-D-arginine vasopressin or placebo to 12 patients with uremia, hemorrhagic tendencies, and prolonged bleeding times. After vasopressin infusion, all patients had shortened bleeding times, with the effect lasting for at least four hours in most cases. Platelet count, platelet cyclic AMP levels, platelet retention on glass beads, plasma fibronectin, serum thromboxane B2 and residual prothrombin, hematocrit, and plasma osmolarity were unchanged after vasopressin. A consistent post-infusion increase in factor VIII coagulant activity and, to a lesser extent, in factor VIII-related antigen and ristocetin cofactor accompanied the shortening of bleeding time. In addition, vasopressin induced the appearance in plasma of larger von Willebrand-factor multimers than those present in the resting state. The compound was given to nine additional patients with acute or chronic renal failure and prolonged bleeding times, before major surgery or renal biopsy. In these patients, shortening of the bleeding time was associated with normal hemostasis. Our findings indicate that 1-deamino-8-D-arginine vasopressin can be used for temporary correction of bleeding time and may prevent surgical bleeding in patients with uremia.

Subunit composition of plasma von Willebrand factor. Cleavage is present in normal individuals, increased in IIA and IIB von Willebrand disease, but minimal in variants with aberrant structure of individual oligomers (types IIC, IID, and IIE).

We have evaluated the subunit composition of plasma von Willebrand factor (vWF) and found evidence that cleavage is present in normal individuals, increased in IIA and IIB von Willebrand disease (vWD), but decreased or absent in variants with aberrant structure of individual oligomers. vWF was rapidly purified from plasma on an analytical scale by monoclonal antibody immunoaffinity chromatography in the presence of protease inhibitors. After reduction and electrophoresis in 5% polyacrylamide gels containing sodium dodecyl sulfate, fragments of 189, 176, and 140 kD, as well as the predominant 225-kD subunit, were identified in plasma vWF from 25 normal individuals. The vWF polypeptides were detected by immunoblotting with a mixture of 55 anti-vWF monoclonal antibodies followed by 125I-rabbit anti-mouse antibody and autoradiography. In five individuals with type IIA and five individuals with type IIB vWD, the proportions of 176 and 140-kD fragments were increased relative to the intact 225-kD subunit, as determined by excising each band and quantitating incorporated radioactivity. In contrast, these fragments were either not detectable or were present in only trace amounts in variants with abnormal structure of individual oligomers (types IIC and IID, and a new variant, type IIE vWD). The results reported here provide evidence that absence of large vWF multimers in these two groups of variants results from different mechanisms. In addition, they demonstrate that partial cleavage of the plasma vWF subunit is a normal event.

Detection of carriers of classic hemophilia using an immunologic assay for antihemophilic factor (factor VIII)

The relation between functional antihemophilic factor (AHF) activity and AHF-like antigen was studied in the plasma of 25 known carriers of hemophilia. In 23 cases, this relationship was significantly different from that in normal women, at the 99% limit of confidence. In contrast, among families in which only one case of hemophilia had occurred, only five of nine mothers could be identified as carriers. This observation suggests that in some instances the hemophilia arose from a newly mutant gene. The data are consistent with the hypothesis that the proportion of antigen to AHF activity in carriers is determined by random activation or inactivation of the X chromosome.

Effects of monoclonal antibodies against the platelet glycoprotein IIb/IIIa complex on thrombosis and hemostasis in the baboon.

To assess the hemostatic consequences and antithrombotic effectiveness of blocking the platelet glycoprotein (GP) IIb/IIIa receptor for fibrinogen and other adhesive glycoproteins in vivo, well characterized murine monoclonal antibodies against the platelet GP IIb/IIIa complex, AP-2 and LJ-CP8, were infused intravenously into baboons. Four animals each received doses of 0.2, 0.4, and 1.0 mg/kg of purified AP-2 IgG, and three animals were given 1.0 mg/kg of the F(ab)2 fragment of AP-2. Five additional animals were given 10 mg/kg LJ-CP8 IgG. At the highest dose, radiolabeled AP-2 IgG bound to an average of 33,000 sites on the circulating platelets. Serial measurements included platelet count, bleeding time, platelet aggregation (induced by ADP, collagen, and gamma-thrombin), and 111In-platelet deposition onto Dacron vascular grafts. Bleeding times were markedly prolonged after injection of 1.0 mg/kg AP-2 IgG (19.2 +/- 3.4 min), 1.0 mg/kg AP-2 F(ab)2 (16.5 +/- 1.8 min), and 10 mg/kg LJ-CP8 (greater than 30 min) vs. control studies (4.6 +/- 0.2 min), and remained prolonged for 48 h. With each antibody platelet aggregation was initially reduced or absent, with partial recovery over 48 h in a manner that was inversely related to dose. AP-2, both whole IgG and F(ab)2 fragment, but not LJ-CP8, caused a dose-dependent reduction (20-46%) in the circulating platelet count over 24 h. Neither AP-2 nor LJ-CP8 caused a reduction in intraplatelet platelet factor 4, beta-thromboglobulin, or [14C]serotonin. Graft-associated platelet thrombus formation was reduced by 73% (1.0 mg/kg AP-2 IgG and 10 mg/kg LJ-CP8) and 53% (1.0 mg/kg AP-2 F(ab)2) relative to control values. In contrast, neither heparin (100 U/kg) nor aspirin (32.5 mg/kg twice a day) showed antithrombotic efficacy in this model. Thus, antibodies that functionally alter the platelet GP IIb/IIIa complex may produce immediate, potent, and transient, antihemostatic, and antithrombotic effects.

Acquired von Willebrand's disease. Evidence for a quantitative and qualitative factor VIII disorder.

Abstract To define further the factor VIII abnormality in acquired von Willebrands disease, we performed immunoelectrophoresis of factor VIII antigen, as well as quantitative measurements of the antigen, factor VIII procoagulant activity and von Willebrand factor activity on plasma from an affected 57-year-old man who also had a poorly differentiated lymphocytic lymphoma. No evidence for an inhibitor against factor VIII procoagulant activity or von Willebrand factor activity was detected, but immunoelectrophoresis showed none of the less anodic forms of factor VIII antigen. There were concomitant decreases in total antigen (0.19 U per milliliter) and von Willebrand factor levels (0.12 U per milliliter). Factor VIII-procoagulant activity was borderline low (0.45 U per milliliter). Correction of both the abnormal immunoelectrophoresis pattern and the quantitative abnormalities followed radiotherapy of the lymphoma. The factor VIII abnormalities might have resulted from binding or destruction of the less an...

von Willebrand factor interaction with the glycoprotein IIb/IIa complex. Its role in platelet function as demonstrated in patients with congenital afibrinogenemia.

We have studied three afibrinogenemic patients, who had only trace amounts of plasma and platelet fibrinogen as measured by radioimmunoassay, and demonstrate here that the residual aggregation observed in their platelet-rich plasma is dependent upon von Willebrand factor (vWF) binding to the platelet membrane glycoprotein (GP)IIb/IIIa complex. The abnormality of aggregation was more pronounced when ADP, rather than thrombin, collagen, or the combination of ADP plus adrenaline was used to stimulate platelets. With all stimuli, nevertheless, the platelet response was completely inhibited by a monoclonal antibody (LJP5) that is known to block vWF, but not fibrinogen binding to GPIIb/IIIa. Addition of purified vWF to the afibrinogenemic plasma resulted in marked increase in the rate and extent of aggregation, particularly when platelets were stimulated with ADP. This response was also completely blocked by LJP5. Addition of fibrinogen, however, restored normal aggregation even in the presence of LJP5, a finding consistent with the knowledge that antibody LJP5 has no effect on platelet aggregation mediated by fibrinogen binding to GPIIb/IIIa. Two patients gave their informed consent to receiving infusion of 1-desamino-8-D-arginine vasopressin (DDAVP), a vasopressin analogue known to raise the vWF levels in plasma by two- to fourfold. The bleeding time, measured before and 45 min after infusion, shortened from greater than 24 min to 12 min and 50 s in one patient and from 16 min to 9 min and 30 s in the other. Concurrently, the rate and extent of ADP-induced platelet aggregation improved after DDAVP infusion. The pattern, however, reversed to baseline levels within 4 h. The concentration of plasma vWF increased after DDAVP infusion, but that of fibrinogen remained at trace levels. We conclude that vWF interaction with GPIIb/IIIa mediates platelet-platelet interaction and may play a role in primary hemostasis.

Leukocyte procoagulant activity: enhancement of production in vitro by IgG and antigen-antibody complexes.

In a variety of immunologic diseases, fibrin-fibrinogen and immune complexes deposit in areas of tissue damage. However, the mechanisms which initiate fibrin-fibrinogen deposition have not been clarified. We find that the procoagulant activity of human leukocytes is markedly increased after incubation with immunoglobulin and immune complexes. This procoagulant activity is evident after 4-24 h incubation in the presence of as little as 0.1 mg/ml of autologous, isologous, or heterologous IgG. At least three of the four subclasses of IgG myeloma proteins are effective. Experiments with purified rabbit and rat antibodies demonstrate that enhancement of procoagulant activity is significantly greater with soluble antigen-antibody complexes than with immunoglobulin alone. In contrast, insoluble complexes are less affective than immunoglobulin alone. Artifacts due to endotoxin contamination of the IgG preparations were excluded on the basis of the differential sensitivities of immunoglobulin and endotoxin to heat and polymyxin B. Evidence is also presented which shows that enhancement of procoagulant activity involves the production, rather than a simple release, of leukocyte procoagulant activity in vitro.

Aberrant multimeric structure of von Willebrand factor in a new variant of von Willebrand's disease (type IIC).

A variant of von Willebrands disease has been identified in which sodium dodecyl sulfate agarose electrophoresis provides evidence that the von Willebrand factor present is structurally abnormal. Rather than the repeating triplet seen in normal subjects and in patients with the IIA and IIB variants, a repeating doublet was present in the propositus. None of the bands had the same mobility as bands in normal subjects or previously described von Willebrands disease patients. The larger multimers of von Willebrand factor were lacking both from plasma and platelets, and did not appear in the circulation after infusion of 1-deamino-[8-D-arginine]-vasopressin. There was a marked increase in the concentration of the smallest multimer in the propositus and his phenotypically normal children, indicating that this abnormality of von Willebrand factor is inherited in an autosomal-recessive manner.

von Willebrand's disease antigen II. A new plasma and platelet antigen deficient in severe von Willebrand's disease.

Factor VIII-related antigen (VIIIag) is deficient in plasma and platelets of patients with severe von Willebrands disease. This study reports a second von Willebrands disease antigen (vWagII), distinct from VIIIag, that is also deficient in the platelets and plasma of patients with severe von Willebrands disease. VIIIag and vWagII are separable by molecular exclusion chromatography, sucrose density gradient ultracentrifugation, and crossed immunoelectrophoresis. They show reactions of immunologic nonidentity with each other, and thus, do not share a precursor-product relationship. vWagII is released from normal platelets during blood clotting, accounting for a fourfold higher concentration of vWagII in serum over plasma.