Hepatitis C antibody and chronic liver disease in haemophilia

A radioimmunoassay was used to detect antibodies to hepatitis C virus (anti-HCV) in 154 patients with haemophilia. Prevalence of anti-HCV was associated with exposure to clotting factor concentrates. 76 of 129 (59%) who had received factor VIII or IX had anti-HCV: 42 of 55 (76%) who required over 10,000 units of concentrate annually had anti-HCV, compared with 34 of 74 (46%) who required less, and 0 of 25 patients who had never received concentrates. Anti-HCV were significantly more common in patients seropositive for antibodies against human immunodeficiency virus (anti-HIV) or with markers of previous hepatitis B infection than in those without anti-HIV or hepatitis B markers (88% vs 39% and 75% vs 46%, respectively). 5 of 23 (22%) haemophiliacs treated only with heated concentrates had anti-HCV compared with 71 of 106 (67%) patients who received unmodified products. 35 patients with chronic liver disease underwent liver biopsy: histological examination showed features associated with post-transfusion hepatitis in 24, all of whom were anti-HCV-positive; of the other 11 patients with no histological features of non-A, non-B hepatitis, 5 were anti-HCV-positive. HCV appears to be the major predisposing factor for most non-A, non-B hepatitis and chronic liver disease in haemophilia.

Selective B-cell depletion with rituximab for the treatment of patients with acquired hemophilia

The activity and safety profile of selective B-cell depletion with rituximab, an anti-CD20 monoclonal antibody, were evaluated in 10 patients with acquired hemophilia. Rituximab was given intravenously at the dose of 375 mg/m(2) once weekly for 4 consecutive weeks. Infusion-related side effects were observed in 3 patients but were of mild intensity and did not require discontinuation of treatment. Eight patients with Factor VIII (FVIII) inhibitor titers between 4 and 96 Bethesda units per milliliter (BU/mL) achieved a complete remission, which was defined as a return to normal FVIII activity and undetectable FVIII inhibitor titers. Two more patients with inhibitor levels greater than 100 BU/mL experienced only a partial transient decrease of the inhibitor after rituximab alone, but they achieved a complete response after being challenged with a combination of rituximab plus pulse intravenous cyclophosphamide. With a median follow-up of 28.5 months (range, 12-41 months), 3 patients have thus far relapsed. Retreatment with the monoclonal antibody at the same dose and schedule resulted in a new sustained response in all these patients. In conclusion, rituximab appears an effective and well-tolerated treatment for patients with acquired hemophilia and low inhibitor titers. A reinforcement of therapy with other agents seems to be required to achieve a full and durable response in those patients with high inhibitor levels.

Gene deletions correlate with the development of alloantibodies in von Willebrand disease

Among all patients with von Willebrand disease (vWD), alloantibodies to von Willebrand factor (vWF) have been described only in severe vWD (type III). The relationship between the development of alloantibodies and the nature of the genetic lesion in vWD is not known. In hemophilia B, large deletions within the factor IX gene appear to correlate with the occurrence of alloantibodies, whereas in hemophilia A no such correlation is apparent. We have studied 19 patients with severe recessive vWD (type III) and 19 with autosomal dominant vWD (type I) by Southern blotting with probes encompassing the full 9 kilobases (kb) of the vWF cDNA. Two apparently unrelated patients were shown to have large deletions within the vWF gene. Both patients had severe vWD (type III) and were the only patients among those studied that had inhibitory alloantibodies to vWF. The extent of deletion was similar in both patients, corresponding to at least the 3'-7.4 kb of the vWF cDNA. The deletion in each patient was estimated to exceed 110 kb. In addition, the localization of the vWF gene to chromosome 12 was confirmed, and a homologous sequence on chromosome 22 was identified.

Diagnostic workup of patients with acquired von Willebrand syndrome: a retrospective single-centre cohort study

BACKGROUND

Diagnosis of acquired von Willebrand syndrome (AVWS) remains challenging. Diagnostic algorithms suggest the use of factor VIII (FVIII:C), von Willebrand factor antigen (VWF:Ag), ristocetin cofactor (VWF:RCo), and collagen-binding capacity (VWF:CB), but the sensitivity of these and other laboratory tests for the diagnosis of AVWS is unknown.

OBJECTIVES

To analyze the capacity of laboratory tests, including point-of-care testing (POCT), for the identification of patients with AVWS.

PATIENTS/METHODS

Thirty-five consecutive patients were enrolled with AVWS diagnosed because of a history of recent onset of bleeding, a negative family history of von Willebrand disease, and abnormal plasma VWF multimers.

RESULTS

According to our inclusion criteria, all patients had bleeding symptoms, and the VWF high molecular weight multimers were either decreased or absent. Regarding POCT, PFA-100 was inconclusive, due to anemia or thrombocytopenia, in 29%; the sensitivity was 80% in the remaining patients. The sensitivity of VWF:Ag (23%), VWF:RCo/Ag ratio < 0.7 (26%), VWF:CB/Ag ratio < 0.7 (46%), anti-VWF antibodies (15%) and VWF propeptide/Ag ratio (22%) was too low to rule out the disease. A combination of VWF:Ag < 50 IU dL(-1), VWF:RCo/Ag ratio < 0.7 and VWF:CB/Ag ratio < 0.8 yielded a sensitivity of 86%. Patients diagnosed only because of abnormal VWF multimers showed similar clinical characteristics as other patients.

CONCLUSIONS

Early diagnosis of AVWS is difficult, due to lack of sensitivity of the tests used. A substantial number of patients present with normal or increased test results, emphasizing the importance of multimer analysis in all patients with suspected AVWS.

Immunoradiometric assay of factor VIII related antigen, with observations in 32 patients with von Willebrand's disease

A solid phase non-competitive immunoradiometric assay (IRMA) has been developed which allows measurement of factor VIII related antigen (VIIIR:AG) levels in normal plasma as low as 2.5 x 10(-4) U/ml. The assay is based on the extraction of VIIIR:AG from test plasma by means of polystrene tubes coated with a specific unlabelled anti-VIIIR:AG rabbit antiserum and subsequent labelling of the extracted antigen with 125I-labelled anti-VIIIR:AG rabbit IgG.

Immunologic studies in von Willebrand's disease. Evidence that the antihemophilic factor (AHF) produced after transfusions lacks an antigen associated with normal AHF and the inactive material produced by patients with classic hemophilia

Antihemophilic globulin (AHF, factor VIII) levels were measured by a standard coagulation assay and by an immunological technique before and serially after infusion of fresh frozen plasma or cryoprecipitate into patients with von Willebrand's disease. Initial levels of AHF, measured both as procoagulant and as antigen, were low. Immediately after transfusions, the rise in levels of AHF-like antigen was compatible with the quantity of antigen present in the infused plasma or cryoprecipitate. Thereafter, levels of antigen declined rapidly and reached preinfusion values in approximately 24 hr. In contrast, procoagulant activity remained elevated, and sometimes continued to rise, for longer periods of time. One possible explanation of this finding is that the AHF molecule produced by patients with von Willebrand's disease, in response to transfusion of as yet unidentified factors, lacks the antigenic site associated with the normal AHF molecule or the inactive molecule produced by patients with hemophilia A.

An immunoradiometric assay for procoagulant factor VIII antigen: results in haemophilia, von Willebrand's disease and fetal plasma and serum

An immunoradiometric assay (IRMA) has been developed based on the inhibitor which arose in a polytransfused severe haemophiliac. The two-site IRMA measures antigens closely associated with the procoagulant parts of the factor VIII complex, which are termed FVIIC antigens or FVIIICAG. FVIIICAG was present in normal plasma and also, at a slightly lower concentration, in normal serum. In 37 patients with haemophilia A, 36 had FVIIICAG levels of less than 10% of the normal plasma pool. In patients with von Willebrand's disease the levels of FVIIIC and FVIIICAG were in good agreement, both before and after treatment with cryoprecipitate or DDAVP. FVIIICAG was relatively stable in plasma at 37 degrees C and could also be detected in cord and fetal serum. The assay is of potential value for detecting reduced levels of factor VIII, for carrier detection and for the prenatal diagnosis of haemophilia.

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 Willebrand's disease. This study reports a second von Willebrand's disease antigen (vWagII), distinct from VIIIag, that is also deficient in the platelets and plasma of patients with severe von Willebrand's 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.

Homozygous and heterozygous deletions of the von Willebrand factor gene in patients and carriers of severe von Willebrand disease

Severe von Willebrand disease is characterized by undetectable or trace quantities of von Willebrand factor in plasma and tissue stores. We have studied the genomic DNA of 10 affected individuals from six families with this disorder using probes from the 5' and 3' ends of the vWF cDNA and with a probe extending from the 5' end into the central region. Southern blots of restriction endonuclease digests and gene dosage analysis measurements carried out with quantitative slot blots of undigested genomic DNA separated these patients into three groups. The first group consisted of a family with complete homozygous deletions of the vWF gene in the four probands. Gene dosage analysis was consistent with heterozygous deletions in both of the asymptomatic parents and four asymptomatic siblings of this kindred (P less than 0.01). The second group was comprised of a family in which there was a complete heterozygous deletion of the vWF gene in the proband and one asymptomatic parent, suggesting that a different type of genetic abnormality was inherited from the other parent. Thus, the patient appeared to be doubly heterozygous for interacting genetic abnormalities affecting vWF expression. In the third group, no gene deletions could be detected. Alloantibodies developed only in the kindred with homozygous deletions. These techniques should prove useful in identifying carriers of severe von Willebrand disease and also in defining patients predictably at risk of developing alloantibodies to vWF.

Factor VIII coagulant activity and factor VIII-like antigen: independent molecular entities

Factor VIII coagulant activity (VIII(C)) and the von Willebrand's disease antigen (Factor VIII-like antigen, vW-Ag) are biologically linked, and it has been suggested that they reside on the same molecule. However, insolubilized human isoantibody to VIII(C) and rabbit antiserum containing antibodies to VIII(C) and vW-Ag differentially bind and remove these entities from plasma, thus physically segregating one from the other. These findings indicate that Factor VIII coagulant activity resides on a molecule distinct from that expressing the von Willebrand's antigen.

Factor-VIII-related antigen: measurement by enzyme immunoassay

Factor-VIII-related antigen was measured, both by an enzyme immunoassay using a microplate method and by the Laurell technique, in normal people, patients with von Willebrand's disease, haemophiliacs, and obligatory haemophilia carriers. The enzyme immunoassay was simpler to perform and gave equally reliable and reproducible results. Many more assays could be carried out at any one time.

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

To define further the factor VIII abnormality in acquired von Willebrand's 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 theless anodic forms of factor VIII antigen by the malignant lymphocytes.

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.

Successful treatment with recombinant factor VIIa of therapy-resistant severe bleeding in a patient with acquired von Willebrand disease

We describe an elderly man who presented with life-threatening hematuria and gastrointestinal bleeding caused by acquired von Willebrand disease associated with monoclonal gammopathy of undetermined significance (MGUS). Standard therapy with desmopressin, von Willebrand factor-containing factor VIII concentrate, tranexamic acid, and immunoglobulin failed to achieve adequate hemostasis. However, treatment with recombinant activated factor VII (rFVIIa) arrested the bleeding completely. Since acquired von Willebrand disease can lead to life-threatening hemorrhage, clinicians should consider rFVIIa as an effective treatment option if standard therapy fails.

Acquired von Willebrand's syndrome: a single institution experience

Acquired von Willebrand's disease or syndrome (AVWS) is a rare bleeding disorder distinguished from congenital von Willebrand's disease by age at presentation and absence of personal and family history of bleeding disorders. We report on 22 patients with AVWS seen over 25 years. Mean age at diagnosis was 61.3 years (range 38-86 years); most patients had a spontaneous or a post-operative hemorrhage at presentation. Gastrointestinal bleeding and epistaxis were the most common spontaneous symptoms. Bleeding time was prolonged in most patients, associated with marked reductions in plasma von Willebrand factor antigen and ristocetin cofactor activity. Plasma VWF multimer distribution was normal (type 1 pattern) in 5 patients, indeterminate (no multimers detectable) in 6 patients (type 3 pattern), and abnormal (decreased higher-molecular-weight multimers, type 2 pattern) in 11 patients. None of 17 patients tested had an inhibitor of ristocetin cofactor activity. An underlying malignant or benign hematologic disease was found in 18 patients, and 1 patient had Crohn's disease. Desmopressin was effective in only half the patients so treated, but all patients responded to treatment with VWF-containing concentrates. Resolution of AVWS occurred with therapy of lymphoma (1 patient) and chronic lymphocytic leukemia (1 patient). Sixteen patients were alive at last follow-up; no deaths were related to bleeding. AVWS may be more prevalent than has been appreciated; we estimate up to 0.04%. Awareness of the existence of AVWS is essential for diagnosis and appropriate management. Therapy of associated diseases may improve the bleeding disorder.

Acquired von Willebrand syndrome: an update

Acquired von Willebrand syndrome (aVWS) is a rare bleeding disorder with laboratory findings similar to those for congenital von Willebrand disease (VWD). However, unlike congenital VWD, it arises in individuals with no personal or family history of bleeding. aVWS occurs in association with a variety of underlying disorders, most frequently in lymphoproliferative disorders, myeloproliferative disorders, and cardiovascular diseases. Through an analysis of the more recent literature data, the pathophysiology and the clinical, laboratory, and therapeutic aspects of this syndrome are concisely reported in this review.

Immunoradiometric assay of procoagulant factor-VIII antigen in plasma and serum and its reduction in haemophilia. Preliminary studies on adult and fetal blood

An immunoradiometric assay (I.R.M.A.) for antihaemophilic factor (factor VIII) has been developed which is based on a human inhibitor to procoagulant factor VIII (FVIIIC) which arose in a polytransfused haemophiliac. The assay detected and measured the antigen related to FVIIIC (FVIIICAg) in normal plasma and serum but failed to detect any antigen in samples from five patients with severe haemophilia. In a sixth patient with severe haemophilia a non-parallel dose-response curve was obtained. FVIIICAg was also present in plasma and serum from six samples of cord blood and in two samples of fetal serum obtained after termination of pregnancy. The assay may, therefore, be used to measure FVIIICAg in small serum samples and provides a potential practical method for prenatal diagnosis of haemophilia.

The effects of epinephrine infusion in patients with von Willebrand's disease

Epinephrine infusion causes variable increases in the components of the Factor VIII (antihemophilic factor) complex in patients with von Willebrand's disease. The increase in antihemophilic factor procoagulant activity was greater than that of Factor VIII-related antigen and von Willebrand factor activity in two patients with von Willebrand's disease. Similar increases in the three individual factors were demonstrated in two other patients. A 4-10-fold increase in Factor VIII-related properties was identified in each of these individuals after infusion. One patient has been studied with very severe von Willebrand's disease; none of the Factor VIII-related properties increased despite two infusions of epinephrine. Bleeding times were normalized or remained normal in the two patients whose von Willebrand factor activity was greater than 25 U/100 ml. It remained prolonged in those three patients whose von Willebrand factor activity levels remained below that concentration. The increase in procoagulant activity was transient in all patients and t 1/2 values were estimated to be between 0.8 and 3.4 h.

Measurement of antihaemophilic factor A antigen (VII:CAg) with a solid phase immunoradiometric method based on homologous non-haemophilic antibodies

Antihaemophilic-factor-A-antibodies, which had spontaneously arisen in 2 patients, were used to develop an immunoradiometric method for measurement of antihaemophilic factor A antigen (VIII:CAg). 13 patients with severe haemophilia A had VII:CAg below the limit of detection (0.01 U/ml). Patients with moderate and mild haemophilia A either had VII:CAg roughly equal to factor VIII clotting activity (VIII:C) or a not detectable VII:CAg, suggesting 2 different molecular mechanisms in moderate and mild haemophilia A. VIII:CAg could be detected in serum but in lower amounts than in plasma. In 2 patients with von Willebrand's disease VIII:CAg equalled VII:C. The post-transfusional retarded increase of VII:C in 1 patient with von Willebrand's disease was accompanied by a slight increase in VIII:CAg. Fetal plasma contained measurable amounts of VII:CAg.