Acquired von Willebrand's disease caused by a monoclonal antibody

Two Rare Complications in One Patient: Acquired von Willebrand Syndrome Associated with Intracranial Plasmacytoma

Here, we describe a rare case of acquired von Willebrand syndrome (VWS) associated with intracranial plasmacytoma. The literature includes reports of a few cases of plasmacytoma with central nervous involvement, but none of them with acquired VWS. Diagnosis was made based on a stereotaxic intracerebral biopsy. During this biopsy, a ventriculoperitoneal shunt was established, which was complicated with abnormal bleeding. Subsequent hemostasis assessment related to hemopathy revealed acquired von Willebrand disease. The patient received induction therapy with bortezomib, thalidomide, and dexamethasone (VTD), followed by high-dose melphalan chemotherapy and autologous stem cell transplantation, and then VTD consolidation, and finally maintenance with lenalidomide. Our patient currently remains in very good partial response without neurological symptoms after 4 months of maintenance. The patient is free of progression 14 months after their original presentation.

Management of bleeding emergencies: when to use recombinant activated Factor VII

Recombinant activated Factor VII (rVIIa) was originally released as a clotting factor, with use limited to a select group of patients who had few other treatment options. Due to the apparent ability of rVIIa to stop bleeding, no matter what the underlying cause, there is great interest in use of rVIIa in a wide range of bleeding patients. This article discusses rVIIa and its uses in a variety of patients, especially liver disease and trauma patients, and makes suggestions for appropriate use. Although most of the reports on rVIIa are anecdotes and case series, there is increasing data for clinical trials to help guide usage.

Acquired von Willebrand Disease in a Patient with Monoclonal Gammopathy of Undetermined Significance

We describe a patient with acquired von Willebrand disease (vWD), who had typical presentation and clinical manifestations of acquired vWD, but correct diagnosis was delayed because of lack of awareness and early recognition. The patient was initially seen at a community hospital with persistent nasal mucosal bleeding and was transfused with an excessive amount of cryoprecipitates before appropriate hemostatic evaluation. Hemostasis work-up revealed that he had classic features of acquired vWD. Further extensive evaluation revealed the patient to have monoclonal gammopathy of undetermined significance (MGUS). He was refractory to a high dose of corticosteroids and had a very transient response to desmopressin acetate (less than 4 hours) but responded well to a high dose of intravenous immunoglobulin (IVIG), which lasted at least 3 weeks with each treatment. He remained very responsive to IVIG 2 years later. His underlying MGUS has not progressed during the past 4 years.

Acquired von Willebrand disease

Acquired von Willebrand disease (AvWD) is a relatively rare acquired bleeding disorder that usually occurs in elderly patients, in whom its recognition may be delayed. Patients usually present predominantly with mucocutaneous bleeding, with no previous history of bleeding abnormalities and no clinically meaningful family history. Various underlying diseases have been associated with AvWD, most commonly hematoproliferative disorders, including monoclonal gammopathies, lymphoproliferative disorders, and myeloproliferative disorders. The pathogenesis of AvWD remains incompletely understood but includes autoantibodies directed against the von Willebrand factor (vWF), leading to a more rapid clearance from the circulation or interference with its function, adsorption of vWF by tumor cells, and nonimmunologic mechanisms of destruction. Laboratory evaluation usually reveals a pattern of prolonged bleeding time and decreased levels of vWF antigen, ristocetin cofactor activity, and factor VIII coagulant activity consistent with a diagnosis of vWD. Acquired vWD is distinguished from the congenital form by age at presentation, absence of a personal and family history of bleeding disorders, and, often, presence of a hematoproliferative or autoimmune disorder. The severity of the bleeding varies considerably among patients. Therapeutic options include desmopressin and certain factor VIII concentrates that also contain vWF. Successful treatment of the associated illness can reverse the clinical and laboratory manifestations. Intravenous immunoglobulins have also shown some efficacy in the management of AvWD, especially cases associated with monoclonal gammopathies. Awareness of AvWD is essential for diagnosis and appropriate management.

Acquired von Willebrand syndromes: clinical features, aetiology, pathophysiology, classification and management

Acquired von Willebrand syndrome (AVWS) associated with hypothyroidism is of type I, results from a decreased synthesis of factor VIII and von Willebrand factor (VWF), responds to desmopressin with normal half-life times for factor VIII and VWF parameters, and disappears after treatment with I-thyroxine. AVWS type I or III, which occurs in a minority of patients with Wilms' tumour in the complete absence of an inhibitor against VWF and no absorption of factor VIII or VWF onto nephroblastoma cells, responds to chemotherapy and/or tumour resection. Hyaluronic acid produced by nephroblastoma cells may be the causative factor in atypical AVWS in Wilms' tumour. AVWS associated with thrombocythaemia of various myeloproliferative disorders is characterized by normal factor VIII and von Willebrand factor antigen (VWF: Ag) levels and a selective deficiency of functional ristocetin co-factor activity (VWF: RCo) and collagen-binding activity (VWF: CBA). AVWS type II in thrombocythaemia is caused by a platelet-dependent proteolysis of large VWF multimers, given the inverse relationship between platelet count and large VWF multimers in plasma and specific increases in the number of proteolytic VWF fragments in plasma. The laboratory findings of AVWS associated with systemic lupus erythematosus or IgG benign monoclonal gammopathy are characterized by a prolonged bleeding time and activated partial thromboplastin time, decreased or absent ristocetin-induced platelet activity, low to very low levels of factor VIII coagulant activity (mean 15%), VWF: Ag (mean 10.7%) and VWF: RCo (mean 6.2%), and a type II multimeric pattern of VWF. Neutralizing and non-neutralizing anti-VWF autoantibodies, usually IgG, have been detected in patient plasma either free or tightly bound to the intermediate and high molecular weight VWF factor VIII particles. The bound auto antibody-antigen complex is rapidly cleared from the circulation, resulting in low levels of factor VIII, VWF parameters as documented by a poor response to desmopressin and VWF factor VIII concentrate. High-dose intravenous immunoglobulin transiently corrects the factor VIII coagulant and VWF levels, lasting for a few weeks in AVWS type II associated with systemic lupus erythematosus or IgG benign monoclonal gammopathy. Prednisolone is effective in AVWS associated with autoimmune disorder. Prednisolone and chemotherapy will not affect AVWS associated with IgG benign monoclonal gammopathy because the monoclonal IgG protein remains to act as an anti-VWF autoantibody. An absorption of VWF to malignant cells has been documented in a few patients with various lymphoproliferative disorders or adrenal carcinoma and suggested to result in a depletion of VWF. The clinical picture of AVWS associated with early-stage IgG multiple myeloma, chronic lymphocytic leukaemia or non-Hodgkin's lymphoma without a paraprotein or no detectable underlying disorder is similar to that of AVWS type II in IgG benign monoclonal gammopathy but poorly documented with regard to the underlying immune mechanism of AVWS. The mechanical destruction of large VWF multimers may be of relevance in conditions in which the shear rate of flowing blood is increased, as may occur in cases of aortic stenosis, other heart valve defects or stenosed vessels. Drug-induced AVWS has been described in association with the use of pesticides valproic acid, ciprofloxacin, griseofulvin, tetracycline, thrombolytic agents and hydroxyethyl starch.

Therapeutic approaches to acquired von Willebrand syndrome

Acquired von Willebrand syndrome (AVWS) is a rare acquired bleeding disorder similar to the congenital von Willebrand disease (VWD) in terms of laboratory findings. Diagnosis of AVWS can be very difficult, with treatment normally taking an empirical form. Although more than 200 cases have been reported since 1968, no retrospective or prospective studies are available on AVWS. Recently, an International Registry on AVWS, gathering data directly from worldwide Departments of Haematology-Oncology and Haemophilia Centres, has been organised by a group working on behalf of the Subcommittee on VWF in the Scientific Standardisation Committee (SSC) of International Society on Thrombosis and Haemostasis (ISTH). Information about an additional 211 AVWS patients is now available, with more detailed data on demography, type of haemorrhage, diagnostic tests for AVWS and management of bleeding episodes. The additional 211 AVWS cases are associated with lymphoproliferative (47%) or myeloproliferative (19%) disorders, cardiovascular diseases, neoplasia (7%) and other miscellaneous diseases (14%). Bleeding episodes of AVWS patients were managed by different compounds including desmopressin (22%), FVIII/VWF concentrates (26%) and high-dose immunoglobulin (10%), plasmapheresis (2%), steroids (5%) and immunosuppressive drugs (20%). Based on complied data, we can conclude that none of the therapeutic approaches proposed are 100% effective in all AVWS cases. Therefore, treatment must be customized for each patient according to the underlying disorder, as well as to the type and the severity of bleeding episode and must be targeted to each specific case.

Idiopathic immune-mediated acquired von Willebrand's disease in a patient with angiodysplasia: demonstration of an unusual inhibitor causing a functional defect and rapid clearance of von Willebrand factor

A case of idiopathic immune-mediated von Willebrand's disease (AvWD) associated angiodysplasia and recurrent lower gastrointestinal bleeding is reported. Coagulation parameters at presentation were activated partial thromboplastin time of 41 sec, bleeding time >15 min, factor VIII procoagulant activity, 5%; von Willebrand factor antigen (WF:Ag) 5%, and vWF:ristocetirn cofactor activity 11% sodium dodecyl sulfate-agarose gel electrophoresis pattern of plasma vWF showed a pattern similar to type II vWD. An in vitro inhibitor against vWF in the immunoglobulin (Ig)G fraction of the patient's plasma was demonstrated vWF parameters showed a short-lived increase after 1-deamino-8-D-arginine vasopressin (DDAVP) administration. The patient's bleeding episodes were initially managed adequately with cryoprecipitate replacement therapy and DDAVP, to which she became refractory. No significant improvement was achieved following the institution of immunosuppressive therapy in the form of high-dose steroids and cyclophosphamide. She was then treated with intravenous immunoglobulin (IvIg) to which she showed an adequate response in terms of her clinical situation and her hemostatic parameters. The patient is on maintenance treatment with repeated courses of IvIg based on vWF parameter monitoring. To our knowledge, this is the third reported association between idiopathic immune-mediated AvWD and angiodysplasia.

Acquired von Willebrand's disease

von Willebrand's disease (vWD) is the commonest inherited bleeding disorder in man with an estimated incidence of 1 per thousand of the population. Acquired von Willebrand's disease (AvWD) is rare with less than 70 cases reported. AvWD is usually associated with autoimmune or clonal proliferation disorders and whilst the precise mechanism of acquired deficiency of von Willebrand factor (vWF) is poorly understood, the most likely candidate mechanism(s) are; antibodies inactivate or form a complex with immunologic or functional sites on vWF, or vWF multimers are selectively absorbed by malignant cells. Unlike hereditary vWD, the acquired form of the disease can be exceedingly difficult to manage. We report 4 cases of AvWD diagnosed at our centre over the past 3 yr. There was no evidence of a previous personal or family history of bleeding in any of the patients and AvWD was confirmed by laboratory testing. All 4 patients had a recognised primary medical condition known to be associated with AvWD (Waldenstrom's Macroglobulinaemia in 2 patients, hypothyroidism in 1 patient and monoclonal gammopathy of unknown significance (MGUS) in 1 patient). The acquired haemostatic defect corrected following treatment of the primary condition in 3 patients with the other patient requiring on demand von Willebrand Factor replacement to control spontaneous and surgery induced bleeding.

Acquired von Willebrand disease: concise review of occurrence, diagnosis, pathogenesis, and treatment

Acquired von Willebrand disease (AvWD) is a rare complication of an autoimmune or neoplastic disease. It is associated mostly with a lymphoid or plasma cell proliferative disorder. The clinical manifestations are similar to congenital von Willebrand disease. Diagnosis is confirmed by the demonstration of decreased levels of factor VIII coagulant activity (VIII:C), ristocetin cofactor activity (vWF:RCo), and von Willebrand factor (vWF) antigen (vWF:Ag). vWF multimer analysis usually reveals a type II defect with decreased abundance of higher molecular weight vWF multimers. Various pathogenetic mechanisms have been described, including the development of anti-vWF antibodies and adsorption of vWF by tumor cells. Successful management approaches have included treatment of the underlying disorder, infusion of high-dose gamma globulin, replacement therapy with factor VIII/vWF concentrates, intravenous infusion of desmopressin, and administration of corticosteroids.

Acquired von Willebrand's disease: a concise review

Acquired von Willebrand's disease (AvWD), an adult-onset bleeding diathesis, has most commonly been found in patients with an underlying lymphoproliferative disease or monoclonal gammopathy. Other malignancies, autoimmune diseases, hypothyroidism, and drugs have also been associated with AvWD. We have included an illustrative case history of a patient with a bleeding diathesis consistent with AvWD and a monoclonal gammopathy who required emergent cardiac surgery. Our review of the literature determined that most cases of AvWD are due to a circulating antibody that combines with the high molecular weight multimers (HMWM) of von Willebrand factor (vWF). These vWF multimer-antibody complexes are subsequently cleared from the circulation either by the reticuloendothelial system or by adsorption onto tumor cells. Clearance of the HMWM of vWF thus results in extremely low functional levels and variable antigenic levels. Mixing studies which are traditionally used to diagnose factor inhibitors are useful only if removal of vWF-antibody complexes can be accomplished in vitro. Treatment with intravenous immunoglobulin has recently been shown to be the most effective therapy for patients with an underlying lymphoproliferative disorder or monoclonal gammopathy. This therapeutic strategy is based on the observed immune complex clearance phenomenon that appears to be operative in most cases. Other AvWD-associated diseases require treatment specifically directed at the underlying disorder.

Coagulation disorders in cancer

Coagulation disorders are common in cancer patients. This article reviews the coagulation laboratory findings in these patients and the thromboembolic and hemorrhagic manifestations of malignancy. Among the many topics addressed are Trousseau's syndrome, disseminated intravascular coagulation, and acquired von Willebrand disease. Pathogenesis of the coagulation disorders and recommendations for treatment of various syndromes are discussed.

Hemostatic abnormalities associated with monoclonal gammopathies

To confirm and expand previous observations about the association of monoclonal gammopathies with hemostatic defects, a prospective evaluation was made in 42 patients with lymphoplasmacytic disorders. The incidence of bleeding complications was low, despite the diversity of abnormal hemostatic tests observed in these patients. Patients with myeloma frequently had abnormal coagulation tests, including thrombin time (64%), fibrin degradation products (32%), platelet aggregation tests with different agonist (30% to 55%), and bleeding time (22%). The lack of platelet response to ristocetin and normal ristocetin cofactor activity in four patients with myeloma may suggest a Bernard-Soulier-type defect. Serum viscosity was negatively correlated with platelet aggregation with collagen, ristocetin, and adenosine diphosphate. In patients with immunoglobulin myeloma, there was a positive correlation between an increased viscosity and a prolonged thrombin time. This study demonstrates the wide variety of coagulation abnormalities in lymphoplasmacytic disorders, usually without significant clinical implications.

Effectiveness of high-dose intravenous immunoglobulin in a case of acquired von Willebrand syndrome with chronic melena not responsive to desmopressin and factor VIII concentrate

A patient with benign monoclonal IgG lambda paraproteinemia, acquired von Willebrand syndrome (AVWS), and chronic melena successfully responding to high-dose intravenous immunoglobulin (lvlg) is reported. Coagulation parameters at admission were APTT (ratio) 1.68; VIII:C 11 IU/dL; vWF:Ag 7 IU/dL:Ricof less than 3 IU/dl. RIPA was greater than 1.8 mg/ml, and bleeding time (BT) was prolonged (18 min). No evidence for an in vitro inhibitor against the VIII/vWF complex was observed. VIII/vWF measurements showed a short-lived increase after both DDAVP and Hemate P, and BT was transiently normalized. After intravenous Ig (1 g/kg for 2 days), VIII/vWF measurements, hemostatic parameters and multimeric pattern were completely corrected (VIII/C 106 IU/dl, vWF:Ag 168 IU/dl, RiCof 147 IU/dl, APTT ratio 0.89, BT 5'), with a return to pre-infusion values after 15 days. Hemoccult test became negative and packed red cell transfusions, of which 130 units were administered during the last year, were no longer required. After 18 months the patient is on maintenance treatment with repeated courses of Ig, at 3 to 4-week intervals based on VIII/vWF and BT monitoring.

Acquired von Willebrand's disease and hypothyroidism: report of a case presenting with menorrhagia

A 17 year old woman presented with severe anaemia due to menorrhagia. On investigation, she was shown to have abnormalities of her haemostatic mechanism consistent with von Willebrand's disease Type I, although there was no family history of this disorder. In addition, she was shown to have severe primary hypothyroidism. On correction of hypothyroidism with oral thyroxine, her coagulation defects returned to normal and menorrhagia ceased. This is consistent with acquired von Willebrand's disease secondary to hypothyroidism.

Study of three patients with monoclonal gammopathies and 'lupus-like' anticoagulants

In three patients with monoclonal gammopathies: a case of multiple myeloma, a case of monoclonal gammopathy of uncertain significance (MGUS) and a case of monoclonal gammopathy associated with lymphocytic lymphoma, we found the presence of a circulating lupus-like anticoagulant. Coagulative studies showed that the paraproteins: an IgG3k, an IgG1k and an IgMlambda, were responsible for the anticoagulant activity by interacting with the thromboplastin phospholipids. Using isoelectrofocusing we demonstrated that the three monoclonal immunoglobulins had a strong basic charge which may have contributed to determining their interaction with the acidic thromboplastin phospholipids. The binding of various phospholipids to the monoclonal proteins was assessed by the fluorescence quenching method which showed heterogeneous specificity. In order to establish whether the electrical charge is also relevant in cases with polyclonal lupus anticoagulant, the polyclonal immunoglobulins were fractionated according to their charge. The strongest inhibitor activity was found in the most basic immunoglobulins. Monoclonal lupus-like anticoagulants represent useful tools for investigating the heterogeneous world of polyclonal lupus-like anticoagulants.

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.

Plasma cell dyscrasias: current status

This is a review of the current status of the monoclonal gammopathies (plasma cell dyscrasias). We begin with the recognition of a monoclonal protein in serum and urine. We briefly discuss the differential diagnosis of the monoclonal gammopathies. Clinical and laboratory findings as well as the management of multiple myeloma are addressed. Future approaches for the treatment of myeloma are provided. The variant forms of multiple myeloma, including smoldering myeloma, plasma cell leukemia, nonsecretory myeloma, IgD myeloma, osteosclerotic myeloma, solitary plasmacytoma of bone, and extramedullary plasmacytoma, are briefly reviewed. Diagnosis and treatment of Waldenström's macroglobulinemia are presented. The recognition and differential diagnosis of the heavy-chain diseases (gamma, alpha, and mu) are included. Monoclonal gammopathy of undetermined significance ("benign" monoclonal gammopathy) is presented in detail. Amyloidosis is not included in this review.

Acquired von Willebrand disease in patients with polycythemia rubra vera

Platelet function and factor VIII complex were evaluated in ten patients with polycythemia rubra vera. Seven patients showed abnormal epinephrine-induced aggregation. The intracellular concentrations of adenosine diphosphate (ADP) were below normal, and the ratio of adenosine triphosphate (ATP)/ADP was greater than normal. In four of eight cases, there was a decrease in ristocetin cofactor activity and a reduction in the slowly migrating forms of vWF:Ag on crossed immunoelectrophoresis. Defect of large multimers of vWF:Ag was also observed. The ratio of vWF:Ag to ristocetin cofactor was elevated in these patients. Plasma from the patients had no effect on normal plasma except in one case, in which isolated IgG appeared to cause inactivation of ristocetin cofactor. Treatment with 1-deamino-8-arginine vasopressin caused correction of the vWF abnormalities with rapid return of ristocetin cofactor to baseline in some patients. The present study shows that the alterations of multimeric structure of vWF occur in more than 50% of patients with polycythemia rubra vera and are in some part due to the inhibitor specific for vWF.

DDAVP in acquired von Willebrand syndrome associated with multiple myeloma

The response to a single intravenous infusion of 1-deamino-8-D-arginine vasopressin (DDAVP, desmopressin) was studied in two patients with acquired von Willebrand syndrome associated with IgG-kappa myeloma. Following infusion of DDAVP (0.3-0.4 micrograms/kg), prolonged bleeding time was normalized; plasma ristocetin cofactor activity, von Willebrand factor antigen, and factor VIII activity were remarkably increased; and high-molecular-weight forms of von Willebrand factor were demonstrated by crossed immunoelectrophoresis in both patients. Excellent hemostasis was achieved following administration of DDAVP in one patient when it was used for the treatment of gum bleeding and for the prophylaxis of bleeding during and after dental extractions. These observations suggest that DDAVP is an effective alternative to blood products for at least some patients with acquired von Willebrand syndrome in addition to patients with inherited von Willebrand disease, hemophilia A, and uremia.

Monoclonal gammopathy with an insulin binding IgG(K) M-component, associated with severe hypoglycaemia

A case is described in which a monoclonal gammopathy was associated with postprandial hypoglycaemia, resulting from insulin binding by the M-component. The monoclonal immunoglobulin possessed a low affinity for insulin, but its binding capacity was very high. Cytotoxic chemotherapy and diazoxide treatment failed to prevent severe hypoglycaemic attacks.

Unique multimeric pattern of von Willebrand factor in a patient with a benign monoclonal gammopathy

A 60-yr-old woman had had a bleeding disorder for the last 13 yr, with laboratory features of monoclonal gammopathy and von Willebrand's disease (vWD). There was no evidence of family vWD. She had a prolonged bleeding time, low levels of factor VIII/von Willebrand factor activities and decreased ristocetin-induced platelet agglutination. Platelet von Willebrand factor (vWF) was normal. Plasma vWF showed a unique multimeric pattern with absence of larger and intermediate multimers and a disproportionate increase of the fastest moving multimer with normal satellite bands, thus differing from previously described types of vWF. No evidence for inhibitor, non neutralizing antibody or proteolytic activity against vWF was found in her plasma or IgG fraction. DDAVP response was very poor. We suggest that this patient had a unique, probably acquired, vWD. Nevertheless the possibility of its being a new subtype of congenital vWD associated with an unrelated monoclonal gammopathy cannot be ruled out.

Acquired von Willebrand syndrome due to an inhibitor specific for von Willebrand factor antigens

A patient with acquired von Willebrand syndrome associated with polycythemia rubra vera is described. Her plasma factor VIII procoagulant activity (67 U/dl) and factor VIII-related antigen (117 U/dl) were normal but no von Willebrand factor activity could be detected. Factor VIII crossed immunoelectrophoresis revealed decreased levels of less anodic polymeric forms of factor VIII. Mixture of her plasma or immunoglobulin G (IgG) fraction with normal plasma resulted in complete recovery of factor VIII activity and related antigen but no measurable von Willebrand factor activity, confirming the presence of an unique inhibitor. The limited specificity of this inhibitor to antigenic sites solely on the von Willebrand portion of the factor VIII bimolecular complex is distinct from all previous reports of this syndrome. This unique inhibitor offers a molecular probe to examine the von Willebrand factor: platelet interaction.

Profound alterations of the multimeric structure of von Willebrand factor in a patient with malignant lymphoma

Laboratory investigation of an acquired haemorrhagic diathesis in a 63-year-old man with malignant lymphoma revealed the classical haemostatic defects found in von Willebrand's disease (vWD). In addition, SDS-agarose gel electrophoresis demonstrated alterations of the von Willebrand factor (vWF) multimeric structure. A profound defect of large and intermediate size multimers was observed which was different from those seen in variants of congenital vWD. In vitro, weak inhibitory activity against factor VIII procoagulant activity and ristocetin cofactor activity was present in the patient's plasma. When patient's plasma was incubated with normal plasma, followed by centrifugation, vWF antigen (vWF:Ag) was precipitated. In vivo, after transfusion of cryoprecipitate, there was rapid plasma clearance of vWF:Ag and ristocetin cofactor and of FVIII coagulant activities.

IgA inhibitor to factor VIII/von Willebrand factor

A 60-year-old Black female presented with a haemorrhagic diathesis and an acquired factor VIII/von Willebrand factor (VIII/vWf) inhibitor. This inhibitor was classified as an IgA immunoglobulin and was active not only against factor VIII coagulant (VIII:C) activity but also against plasma von Willebrand factor (vWf). The purified IgA also interacted with normal platelets to inhibit ristocetin-induced platelet aggregation (RIPA). In contrast, studies with haemophilia A plasma and platelets revealed that the inhibitor did not react significantly with these plasmas or platelets. The significant differences in the inhibition of vWf assay both of the plasma and the platelets of the haemophilia A patients suggests that part of the haemorrhagic diathesis may be related not only to the inhibition of VIII:C but also to interference with platelet function. In addition, these studies suggest that there may be significant differences in the factor VIII-related antigen (VIII R:Ag) on platelets in haemophilia A patients compared to normal.

Acquired von Willebrand's disease: demonstration of a circulating inhibitor to the factor VIII complex in four cases

We have studied four patients suffering from acquired von Willebrand's disease. All patients had a severe bleeding diathesis with recurrent life-threatening haemorrhages. Three of the patients had a monoclonal gammopathy and one of these developed multiple myeloma. In three patients tested, a plasma inhibitor to ristocetin cofactor activity was detected. In each case this was localized to the IgG fraction of plasma. In addition, VIII:C activity was found to be associated with the IgG fraction of patients' plasma and altered mobility of VIII:C was detected on Laurell immunoelectrophoresis. Furthermore, plasma from all four patients and the IgG fraction therefrom resulted in a dissociation of normal VIII:C into two components separable by gel-filtration on Sepharose 6B. Finally the circulating half-life of the three factor VIII activities was found to be markedly reduced in the patients with acquired von Willebrand's disease. We conclude that in the patients studied the coagulation defect was related to the presence of a circulating inhibitor to the factor VIII complex and that this inhibitor was associated with the IgG fraction of plasma.

Pathogenesis of antibody-induced acquired von Willebrand Syndrome

A patient with clinical and laboratory evidence of von Willebrand syndrome is described in association with an IgG-kappa immunoglobulin and Bence-Jones proteinuria due to a probable lymphoproliferative disorder. He had a persistently prolonged bleeding time of greater than 20 minutes, factor VIII related antigen (VIII:R.Ag), factor VIII procoagulant activity (VIII:C) and factor VIII ristocetin co-factor (VIIIR:Rcof) below 10%. Following cryoprecipitate or high purity factor VIII concentrate infusion, he had the expected immediate rise in VIII:C, VIII:R.Ag, and VIIIR:Rcof, but there was a rapid decline in all three components within two hours. The larger forms of VIII:R.Ag were preferentially removed from the plasma, and this paralleled the fall in plasma VIIIR:Rcof level. However, no inhibitory activity could be demonstrated in vitro using the patient's plasma or IgG. Using protein A it was possible to demonstrate that his plasma or IgG bound factor VIII and that this complex retained its biological activity in vitro. It is postulated that the monoclonal IgG forms complexes with factor VIII in vivo and these are rapidly removed by the reticuloendothelial system (RES).

Acquired, transient factor X (Stuart factor) deficiency in patient with mycoplasma pneumonial infection

A case of severe haemorrhagic diathesis due to acquired deficiency of factor X (both immunologically and in procoagulant activity) is presented. The clinical and serological features of this case indicated mycoplasma pneumonial infection. Factor X in the peripheral blood did not appear to be influenced by administration of vitamin K, prothrombin-complex concentrate, fresh plasma or fresh whole blood. Circulating inhibitors of blood coagulation were absent and systemic amyloidosis could not be demonstrated. After 20 d, factor X spontaneously returned to normal. In view of the absence of other known causes of factor X deficiency, a possible relationship with mycoplasma pneumonial infection is suggested.