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.     

Lactobacillus plantarum endocarditis in a patient with benign monoclonal gammopathy

A patient with Lactobacillus plantarum endocarditis who responded to initial treatment with penicillin G and netilmicin without relapse is reported. Bacteriological and clinical aspects of lactobacillus endocarditis and the finding of benign monoclonal gammopathy in the patient are discussed.     

Canine von Willebrand factor expresses a multimeric composition similar to human von Willebrand factor

Canine von Willebrand factor (vWf) was compared to human vWf. Antisera raised against human vWf or canine vWf cross-reacted with both heterologous proteins and reactions of partial identity were seen using crossed immunoelectrophoresis. Similar patterns of multimerization were obtained for vWf from both canine and human sources using the enzyme-linked immunoelectrotransfer blot method. However, the canine protein displayed an altered electrophoretic mobility. The molecular weight of the vWf monomer was estimated by SDS-PAGE and found to be indistinguishable from that of human vWf monomer. Canine vWf is decreased in animals with clinically evident hypothyroidism and in heterozygous "carriers" of von Willebrand's disease (vWd) that display no clinical symptoms of vWd. Results expand the concept that von Willebrand's disease in dogs may be a useful model for study of vWd in humans, and that immunochemical methods established for studies of human vWf appear appropriate for studies of canine vWf.     

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.     

Pure red cell aplasia with monoclonal gammopathy and von Willebrand disease

We report a case of pure red cell aplasia (PRCA) with benign monoclonal gammopathy (BMG) of IgA.lambda type and type I von Willebrand disease (vWD). A 61-year-old female patient was treated initially with prednisolone, azathioprine and cyclophosphamide with transient and unsatisfactory reticulocyte response. Oral administration of 200 mg of cyclosporine A (CyA)/day was started from July, 1987. A rapid and marked reticulocytosis was seen from a week later and there was a rapid increase in hemoglobin levels, and remission has been maintained for over 22 months. Patient's serum and IgA taken on admission did not show inhibitory activity to both CFU-E growth from her own bone marrow cells obtained in remission and von Willebrand factor. T cell-mediated suppression to CFU-E growth was detected. On family study, the patient's second son was found to be a type I vWD. These results indicate that there is no direct causal relationships between BMG and PRCA or vWD, and that CyA may have a place in the management of PRCA.     

Unique interactions of asialo von Willebrand factor with platelets in platelet-type von Willebrand disease

The present studies demonstrate that platelets from patients with platelet-type von Willebrand disease show specific and saturable binding of asialo von Willebrand factor (AS-vWF) under conditions where such binding is not observed with normal platelets. Although specific binding of 125I-AS-vWF to formalin-fixed normal platelets could not be demonstrated, specific binding to fixed patient platelets was seen with an apparent Kd of 1.3 micrograms/mL and specific maximally bound ligand of 0.40 micrograms/10(8) platelets. Preincubation of patient platelets with the antiglycoprotein Ib (anti-GPIb) monoclonal antibody AS-2 reduced total binding close to the level of computer-estimated nonspecific binding. In contrast, binding was not reduced by preincubation with anti-GPIIb/IIIa monoclonal antibody or with 5 mmol/L EDTA. Under stirring conditions, the binding of AS-vWF to fixed patient platelets was accompanied by a strong agglutination response. AS-vWF- induced agglutination was similarly observed in patient but not normal platelet-rich plasma (PRP) in the presence of 5 mmol/L EDTA. In the absence of EDTA, AS-vWF produced a full aggregation response in patient PRP at concentrations as low as 0.1 microgram/mL in contrast to the 2 to 20 micrograms/mL required by normal PRP. Both thromboxane B2 formation and adenosine triphosphate secretion showed an AS-vWF concentration dependence paralleling the aggregation responses. These studies show that a major difference in the platelets from patients with platelet-type von Willebrand disease is the presence of an exposed, high-affinity binding site associated with GPIb that recognizes AS-vWF.     

Hypoglycaemia caused by atypical insulin antibodies in a patient with benign monoclonal gammopathy

Abstract. We describe a 48-year-old woman with recurrent severe hypoglycaemia apparently caused by a paraprotein with insulin-binding capacity. Very high fasting values were found for serum insulin (170 and > 250 mU l^?1) as well as for proinsulin 125 pmol l^?1 and an insulinoma was suspected. Hypoglycaemia developed after an oral glucose tolerance (OGTT) test but not during fasting for 48 h. Free insulin and C-peptide were normal during OGTT whereas serum insulin was very high. ¹²⁵I-insulin binding to serum, determined with a polyethylene glycol (PEG) precipitation method was high (40%), and equally high after addition of 1.7 × 10^?5 mol l^?1 cold insulin to estimate non-specific binding. By adding very high concentrations of cold insulin, displacement of ¹²⁵I-insulin bound to serum was found (50% displacement at 4 × 10^?5 mol l^?1). No immunoglobulin G (IgG) insulin antibodies were detected by radio-immunoelectrophoresis. On agarose electrophoresis a small paraprotein (4 g l^?1) in the γ-globulin fraction was detected. ¹²⁵I-insulin binding to this paraprotein was demonstrated. We conclude that if insulin autoantibodies are suspected as a cause of hypoglycaemia screening for insulin antibodies should always be done with a PEG-precipitation method.     

The complex multimeric composition of factor VIII/von Willebrand factor

We have analyzed the multimeric structure of factor VIII/von Willebrand factor in plasma by sodium dodecyl sulfate electrophoresis using gels of varying porosity and a discontinuous buffer system. Factor VIII/von Willebrand factor bands were identified by reaction with 125I-labeled affinity-purified antibody and subsequent autoradiography. In 1% agarose gels, normal plasma displayed a series of sharply defined oligomers. However, increasing the agarose concentration to 2.0% or utilizing mixtures of 0.8% agarose--1.75% acrylamide revealed two bands of lesser intensity interposed between the major bands. When the acrylamide concentration in the gels was increased to 2.5%, bands with a faster mobility than IgM and fibronectin were now evident. Type IIA von Willebrand's disease showed not only an absence of the larger multimers but also a relative increase in several of the newly identified bands as compared to type IIB, type I, and normal. These studies suggest that factor VII/von Willebrand factor in IIA von Willebrand's disease is structurally different from that in other forms of the disorder. They also indicate that the multimeric composition of factor VII/von Willebrand factor is more complex than can be explained by simple linear polymerization of a single protomer.     

Acquired von Willebrand syndrome associated with monoclonal gammopathy: a single-center study of 36 patients

In this single-center retrospective study, we evaluated the accuracy of laboratory tests in diagnosing acquired von Willebrand syndrome associated with lymphoproliferative disorders in 36 consecutive patients diagnosed at the University Hospital of Nantes, France. We also compared hemostatic treatments in the following groups: 21 patients with Waldenstr?m macroglobulinemia (WM), 14 with monoclonal gammopathy of undetermined significance (MGUS) (10 with IgG-MGUS and 4 with IgM-MGUS), and 1 with IgA multiple myeloma (IgA-MM). The diagnosis was made in 18 (50%) patients during systematic screening, in 6 (17%) during active mild hemorrhage, and in 12 (33%) during an active, severe bleed. Of the laboratory tests studied, only closure times measured on the Platelet Function Analyzer (PFA)-100 device reliably diagnosed the hemostatic problem. There was no relationship between the factor VIII activity (FVIII:C) or von Willebrand factor activity (VWF:RCo) levels and the previous history of hemorrhage described by patients.We studied hemostatic treatment in most patients: IgG-MGUS patients responded well to high-dose intravenous immunoglobulin (IVIg) infusions (1 g/kg per d), although patients with IgM-MGUS did not. Desmopressin infusions were effective in 3 patients with IgG-MGUS and 2 patients with IgM-MGUS when the baseline values were above 10 IU/dL, but levels soon returned to the baseline. The 7 WM patients had a good response to desmopressin. These results confirm the efficacy of IVIg in IgG-MGUS patients and the prominent role of closure time in the diagnosis of acquired von Willebrand syndrome.     

Assembly of multimeric von Willebrand factor directs sorting of P-selectin

We designed a model system to study the role of von Willebrand factor (vWF) in the sorting of P-selectin and the biogenesis of Weibel-Palade body (WPB)-like organelles. For that purpose, a human epithelial cell line (T24) that synthesizes P-selectin mRNA, but which is devoid of vWF mRNA synthesis and storage organelles, was transfected with full-length vWF cDNA or a deletion mutant thereof. Stable transfectants of T24 with full-length vWF cDNA revealed the generation of WPB-like organelles as demonstrated by colocalization of vWF and P-selectin with double-labeling immunofluorescence. In contrast, T24 cells transfected with vWF delD'D3 cDNA, encoding a mutant that is unable to form vWF multimers, displayed only perinuclear vWF staining, whereas no indication was found for the presence of WPB-like organelles. The contents of the organelles in full-length vWF cDNA-transfected T24 cells were released on activation of the protein kinase C pathway, similar to the situation with genuine endothelial cells. The expression of vWF did not affect the biosynthesis of P-selectin, as deduced from the observation that untransfected and vWF cDNA-transfected T24 cells contained the same amount of P-selectin mRNA. We propose that the biosynthesis of multimeric vWF directs the generation of WPB-like organelles, as evidenced by the sequestering and anchoring of P-selectin into these storage granules.     

Immune-mediated etiology of acquired von Willebrand syndrome in systemic lupus erythematosus and in benign monoclonal gammopathy: therapeutic implications

The most common nonimmune etiology of acquired von Willebrand syndrome (AvWS) includes hypothyroidism, Wilms' tumor, thrombocythemia, or congenital heart defects, and the use of various drugs. AvWS type 1 in patients with hypothyroidism is due to decreased Willebrand factor (vWF) synthesis and is reversible by treatment with thyroxin. AvWS type 1 or 3 in children with Wilms' tumor disappears after successful chemotherapy or tumor resection but the mechanism of the vWF deficiency is unknown. The AvWS type 2 in patients with thrombocythemia of various myeloproliferative disorders is caused by increased proteolysis of large vWF multimers at increasing platelet counts to above 1000 x 10 (9)/L. Reduction of platelet counts to normal results in correction of the vWF parameters together with disappearance of the bleeding tendency. Type 2-like AvWS in children with congenital heart valve defects is caused by shear stress-induced proteolysis of large vWF multimers and is reversible after surgical correction. AvWS associated with the use of drugs disappears after discontinuation of the causative agent. Immune-mediated AvWS is associated with either systemic lupus erythematosus (SLE) or immunoglobulin G (IgG) benign monoclonal gammopathy (BMG), and usually shows a type 2 vWF deficiency. Using a simple enzyme-linked immunosorbent assay, an IgG antibody against vWF is detectable in AvWS associated with SLE and IgG BMG. The IgG-autoantibody-factor (F) vWF/VIII complex is rapidly cleared from the circulation, which explains the combined FVIII:coagulant activity (C) and vWF deficiency and the poor responses of FVIII:C and vWF parameters to intravenous desmopressin acetate and vWF/FVIII concentrates. A transient correction of both FVIII:C and vWF parameters to normal for a few weeks after high-dose intravenous immunoglobulin is seen in AvWS associated with SLE and IgG BMG. AvWS associated with SLE uniformly shows a curative response to corticosteroids. AvWS associated with IgG BMG does not respond to corticosteroids, immune suppression, or chemotherapy. AvWS associated with IgM BMG is rare and does not respond to any conventional treatment.     

Canine platelet von Willebrand factor: quantification and multimeric analysis

Washed canine platelets were shown to express a significant level of von Willebrand factor (vWf). Canine platelet vWf differed from canine plasma vWf by the absence of satellite bands associated with each multimer when resolved by SDS-agarose gel electrophoresis. Expression and multimeric composition of canine platelet vWf was quite similar to that of human platelet vWf. Quantification in both lysed, washed canine platelets and in releasate of washed canine platelets yielded estimates of platelet vWf at approximately 2% of circulating vWf in this species, with approximately 15% of this being released into the fluid phase on activation. This contrasts with findings in humans, in which approximately 10%-25% of circulating vWf is compartmentalized in platelets. The difference in relative levels of canine and human platelet vWf could not be accounted for by differences in platelet ultrastructure. The decreased relative level may account for reports that canine platelets contain no vWf.     

Acquired von Willebrand syndrome in patients with monoclonal gammopathy of undetermined significance investigated using a mechanistic approach

BackgroundAcquired von Willebrand syndrome (AVWS) has been reported to occur in association with monoclonal gammopathy, usually of undetermined significance (MGUS). It may present as a type 1 or type 2 von Willebrand factor (VWF) defect depending on the patient’s representation of large VWF multimers.Materials and methodsThe mathematical model by Galvanin et al., already employed for studying inherited von Willebrand disease (VWD), was used to explore the pathogenic mechanisms behind MGUS-associated AVWS.ResultsThe patients studied showed significantly reduced VWF levels and function; an increased VWF propeptide to VWF antigen ratio; and all VWF multimers present but in reduced quantities, with the low-molecular-weight VWF forms being significantly more represented than those of higher molecular weight. Our mathematical model revealed a significantly increased VWF elimination rate constant, with values similar to those of type Vicenza VWD. An even more increased VWF proteolysis rate constant was observed, with values one order of magnitude higher than in type 2A VWD but, in contrast, no loss of large multimers. The model predicted the same elimination rate for high- and low-molecular-weight VWF multimers, but proteolysis of the high-molecular-weight forms also contributes to the pool of low-molecular-weight oligomers, which explains why they were relatively over-represented.DiscussionIn MGUS-associated AVWS the increase of both clearance and proteolysis contributes to the circulating levels and multimer pattern of VWF, with a phenotype that appears to be a combination of type Vicenza and type 2A VWD. Hence, the mechanisms behind the onset of AVWS seem to differ from those of inherited VWD.     

Acquired von Willebrand disease in a patient with angiodysplasia resulting from immune-mediated clearance of von Willebrand factor

A patient with a severe bleeding tendency due to acquired von Willebrand disease (VWD) is presented. Although no underlying disorder has emerged during 6 years of follow-up, an immune-mediated mechanism was responsible for acquired VWD in this patient as demonstrated by detection of von Willebrand factor (VWF)/anti-VWF complexes in the patient's plasma and their removal by protein A–sepharose beads and resumption of normal haemostasis with correction of VWF antigen, VWF activity and VWF multimeric pattern after treatment of the patient with high-dose gammaglobulin. Detection of anti-VWF antibodies in the patient's plasma had a significant impact on the choice of therapeutic intervention to control bleeding.     

Life-threatening reaction to factor VIII concentrate in a patient with severe von Willebrand disease and alloantibodies to von Willebrand factor

A 16-yr-old girl with severe von Willebrand disease complicated by the development of precipitating alloantibodies to von Willebrand factor (anti-VWF) had a life-threatening anaphylactoid reaction immediately after the infusion of a commercial plasma concentrate of factor VIII/von Willebrand factor. An early post-infusion activation of the complement system was demonstrated by the appearance of C3 split products and by the drop of serum CH50 activity, occurring in parallel with a post-infusion drop in the anti-VWF antibody levels. Immune complexes remained unchanged in the early post-infusion period and rose to a moderate extent only after 24 h. We conclude that biologically active products of the complement system contributed to the onset of this life-threatening reaction which occurred after concentrate infusion.