Inhibitor development in patients with congenital factor VII deficiency, a study on 50 Iranian patients.

: Congenital factor VII (FVII) deficiency is a rare bleeding disorder with an estimated prevalence of 1 per 500 000 in the general population. On-demand replacement therapy is the main therapeutic choice in patients with congenital FVII deficiency. Inhibitor formation against exogenous FVII is very rare and can cause challenges in the management of the disorder. The present study was conducted to assess the prevalence of FVII inhibitor in 50 patients with congenital FVII deficiency under on-demand or prophylaxis treatment by recombinant activated FVII. All patients with confirmed congenital FVII deficiency were assessed for inhibitor development in regular intervals. Inhibitor titer was determined by a modified Nijmegen-Bethesda assay. The study results were analyzed by SPSS software. Among all cases, two patients (4%) developed an FVII inhibitor. Case 1 was a 14-year-old boy with severe FVII deficiency (FVII activity <1%) with regular prophylaxis. The patient was a high-responder with high-titer FVII inhibitor (170 Bethesda Unit). This patient, who had a history of intracranial hemorrhage, had undergone brain surgery three times. The second patient was a 70-years old man with on-demand therapy that also developed a high-titer inhibitor (10 Bethesda Unit). This patient had experienced easy bruising and endured a few surgeries for his brain tumor and, finally, succumbed to the disease. Although the inhibitor formation is a rare phenomenon, it may result in a significant challenge to manage the affected patients.

CD32 inhibition and high dose of rhFVIII suppress murine FVIII-specific recall response by distinct mechanisms in vitro.

Development of neutralising antibodies (inhibitors) against factor VIII (FVIII) is a frequent and severe complication of replacement therapy in haemophilia A. Previous data from haemophilia A mouse model demonstrates that both CD32 inhibition and high doses of rhFVIII prevent the differentiation of FVIII-specific memory B cells (MBCs) into antibody secreting cells (ASCs). Here, cellular targets responsible for the suppression of ASC formation by means of CD32 inhibition and high dose of rhFVIII were analysed. We investigated apoptosis on FVIII-specific MBCs using a pan caspases inhibitor, and screened for defects in rhFVIII presentation by analysing T cell release of Th1- and Th2-cytokines in vitro. Although high dose of rhFVIII suppressed ASC formation, cytokine response was not affected. Upon re-stimulation of splenocytes with high dose of rhFVIII, prevention of apoptosis fully restored the FVIII-specific recall response. In contrast, genetic deletion or inhibition of CD32 significantly altered Th1- and Th2-response. CD32 blockade and inhibition of apoptosis resulted in a partial rescue of FVIII-specific ASCs. Normal cytokine secretion could not be restored. In conclusion, suppression of FVIII-specific recall response by CD32 and high doses of rhFVIII is mediated by distinct mechanisms. High dose of rhFVIII induces apoptosis in FVIII-specific MBCs but does not influence FVIII-specific T cell response. CD32 blockade, however, may suppress the FVIII-specific recall response by two ways: i) increasing apoptosis of FVIII-specific MBCs and ii) disturbing FVIII-specific T cell response by modulating presentation of rhFVIII to CD4+ T cells in vitro.

Isotypic analysis of antibodies against activated Factor VII in patients with Factor VII deficiency using the x-MAP technology.

While the immune response to hemophilic factors in hemophilia has been widely studied, little is known about the development of anti-Factor VII (FVII) antibodies in FVII deficiency. We developed a robust technique based on the x-MAP technology to detect the presence of antibodies against FVII and characterize their isotype and validated this method using blood samples from 100 patients with FVII deficiency (median FVII clotting activity [FVII:C]: 6%) and 95 healthy controls. Anti-FVII antibodies were detected in patients but also in some controls, although the concentration of total immunoglobulin G (IgGt) and IgG1 and IgG4 subclasses was significantly different between groups. The IgG1 subclass concentrations remained significantly different also when only untreated patients were compared with controls. This difference could partially be related to the F7 genotype, particularly in patients harboring the p.Arg139Gln mutation. This x-MAP-based method might be useful for assessing the immunogenicity of novel FVII compounds and of activated FVII (FVIIa) concentrates. Further prospective studies are needed to better understand the clinical relevance of these antibodies in the management of patients with FVII deficiency.

Acquired factor VII deficiency associated with acute myeloid leukemia.

Isolated acquired factor VII deficiency is a rare coagulopathy. It has been reported in 31 patients with malignancy, sepsis, postoperatively, aplastic anemia, and during bone marrow transplantation. We discuss, through a new case of acquired factor VII deficiency, the characteristics of this disease when it is associated with acute myeloid leukemia. Acquired factor VII deficiency in hematological diseases can be caused by intensive chemotherapy, infections, or hepatic dysfunction. The best treatment in developing countries remains corticosteroids associated with plasma exchange, frozen plasma, and antibiotics.

Molecular analysis in a patient with severe factor VII deficiency and an inhibitor: report of a novel mutation (S103G).

Congenital factor VII (FVII) deficiency is an autosomal recessive bleeding disorder with variable phenotypic correlation between FVII activity and bleeding risk. We report a novel mutation of the FVII gene that creates the amino acid change Ser 103 to Gly, which resulted in severe FVII deficiency with reduced FVII antigen. This mutation in the heterozygous form was also present in a mildly affected, unrelated patient. We also report on the natural history of an FVII inhibitor in the patient with severe FVII deficiency.

A coagulation factor VII deficiency protects against acute inflammatory responses in mice.

Upregulation of the activated Factor VII (FVIIa)/Tissue Factor complex, downregulation of natural anticoagulation pathways, and inhibition of fibrinolysis, are major contributors to coagulopathies associated with acute inflammation. Provision of FVIIa, and consequent downstream coagulation-related proteases, also stimulates further inflammatory changes, which can result in disseminated intravascular coagulation. Thus, the potential protective effects in vivo of a genetic-based reduction in FVII levels have been investigated in a murine model of acute inflammation, namely lipopolysaccharide (LPS)-induced lethal endotoxaemia. Mice with a total FVII deficiency do not survive the neonatal period. Therefore mice expressing low levels of FVII (FVII(tTA/tTA)), producing sufficient amounts of FVII for survival (approximately 5% of wild-type (WT) FVII), were employed to investigate in vivo pathways involved in the crosstalk between coagulation, inflammation, and survival, consequent to administration of a lethal dose of LPS. The FVII(tTA/tTA) mice presented with reduced mortality, coagulation, and inflammatory responses in comparison with similarly treated WT mice after administration of LPS. The attenuated inflammatory responses in FVII(tTA/tTA) mice were associated with downregulation of Egr-1 signalling. Administration, in vivo, of specific inhibitors of FXa and thrombin demonstrated that the inflammatory responses were unaltered in WT mice, but further reduced in FVII(tTA/tTA) mice. Therefore, a FVII deficiency enhances survival from lethal endotoxaemia both through attenuation of inflammatory responses that result directly from reduced FVIIa levels, and, indirectly, from downregulation of coagulation proteases downstream of the FVII-dependent cascade.

Life-threatening bleeding in a case of autoantibody-induced factor VII deficiency.

A male patient presented with life-threatening bleeding induced by autoantibody-induced factor VII (F.VII) deficiency. This patient had macroscopic hematuria, skin ecchymosis, gastrointestinal bleeding, and a neck hematoma that was causing disturbed respiration. He developed acute renal failure and acute hepatic failure, probably due to obstruction of the ureters and the biliary tract, respectively. Although activated partial thromboplastin time was normal, prothrombin time (PT) was remarkably prolonged at 71.8 seconds compared to 14.0 seconds in a normal control. Both the immunoreactive level of F.VII antigen and the F.VII activity of the patient's plasma samples were < 1.0% of normal. Although an equal part of normal plasma was added to the patient's plasma, PT was not corrected. The patient's plasma inhibited F.VII activity. These findings suggested the presence of a plasma inhibitor for F.VII. After administration of large doses of methylprednisolone, PT was gradually shortened and plasma levels of F.VII increased over time. Bleeding, acute renal failure, and acute hepatic failure improved markedly following the steroid treatment. These observations suggest that life-threatening bleeding can be induced by autoantibody-induced F.VII deficiency and that immunosuppressive therapy using large doses of steroid can be successful in inhibiting the production of the autoantibody.

[Alexander's disease]. / La maladie d'Alexander.

Alexander disease, or hypoproconvertinemia is a rare autosomic recessive coagulation disorder. The features include familial and/or personal history of bleeding, with an abnormal prothrombin period and a normal activated partial thromboplastin period. Coagulation and genetic studies allow subclassification with prognosis incidence for this disease. The authors report on a case of one family with Alexander disease.

Monoclonal antibodies to human factor VII: a one step immunoradiometric assay for VII:Ag.

Three mouse monoclonal antibodies (RFF-VII/1, RFF-VII/2, and RFF-VII/3) which bind specifically to different epitopes on human factor VII antigen were raised. Two of the antibodies, RFF-VII/1 and RFF-VII/2, bound strongly to factor VII antigen (VII:Ag), but only RFF-VII/1 and RFF-VII/3 were potent inhibitors of factor VII coagulation activity (VII:C). RFF-VII/1 and RFF-VII/2 were used in a one step, double monoclonal immunoradiometric assay for VII:Ag. This was highly reproducible and detected as little as 0.05U/dl VII:Ag. Values for VII:Ag obtained for plasma samples from normal subjects (n = 20), patients with liver disease (n = 20), patients treated with warfarin (n = 20), and those congenitally deficient in factor VII (n = 7) correlated very well (r = 0.96) with data obtained in a radioimmunoassay using polyclonal rabbit antiserum to factor VII. This simple and sensitive monoclonal antibody based assay offers a convenient method for the detection of VII:Ag in various disease states.

Factor VII activity and antigen in a patient with abnormal factor VII.

A patient with abnormal factor VII, which showed different activity when thromboplastin from different sources was used, is reported. The propositus, who was first seen at routine health examination 1 month after delivery, was a girl with no complaints of bleeding. The coagulation pattern was characterized by an abnormal clotting time using Normotest reagent which did not respond to the administration of vitamin K. Factor VII activity was decreased when measured using rabbit brain and lung thromboplastin, mildly decreased using human brain or human placenta thromboplastin and within the normal range using ox brain thromboplastin. The level of factor VII antigen was normal and revealed a normal mobility on immunoelectrophoresis. The molecular weight of this factor VII was not different from normal factor VII when analysed using autoradiography after sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). It seems probable that the propositus had an abnormality similar to the factor VII Padua 1 described previously.

Electroimmunoassay of factor VII antigen.

A clear precipitating arc of factor VII antigen appeared by immunoelectrophoresis using 125I-labelled anti-factor VII antibody incorporated in the Laurell plate to enhance the sensitivity. A plasma sample could be electrophoresed directly on 1% agarose containing 1% rabbit anti-human factor VII antiserum, 0.1% 125I-labelled anti-human factor VII specific IgG and 0.5% polyethyleneglycol 6000, and after washing, autoradiographed at -70 degrees C for 24 hr. A distinct rocket was seen from 45 ul standard reference plasma to 16-fold after auto-radiography. Of 4 patients with congenital factor VII deficiency, 3 patients had no detectable factor VII antigen, one patient had reduced factor VII antigen.

Studies on immunological assay of vitamin K dependent factors. I. Measurement of factor VII antigen by radioimmunoassay.

A radioimmunoassay (RIA) for factor VII was developed using 125I-factor VII, anti-factor VII rabbit serum and anti-rabbit IgG goat serum. The lower limit of sensitivity in normal reference plasma was 3 X 10(-3) units/ml. Although the level of factor VII antigen (VII:Ag) in normal plasma samples (n = 20) 0.944 +/- 0.176 units/ml, correlated with that of factor VII coagulant activity (r = 0.89), VII:Ag level in paired normal sera showed a higher value (1.469 +/- 0.376 units/ml). The level of antigen according to RIA of factor VIIa activated by factor Xa increased 2.5-fold compared with that of unactivated factor VII. It is suggested that the polyclonal anti-factor VII produced in a rabbit had higher affinity for factor VIIa than for factor VII. In two out of seven patients with congenital factor VII deficiency, VII:Ag was detectable (0.04, 0.31 units/ml, respectively) whereas VII:C was less than 0.01 units/ml. In 12 warfarin-treated individuals, VII:C showed a lower level (0.121 +/- 0.063 units/ml) that that of VII:Ag (0.518 +/- 0.186 units/ml). During 4 weeks observation after stopping warfarin, VII:C and VII:Ag reached normal levels in 1 week. However, VII:C did not reach equivalence with VII:Ag until 4 weeks had elapsed.

Carrier detection in factor VII congenital deficiency.

Thirty obligate and 28 possible carriers of factor VII congenital deficiency, belonging to 16 families, were studied in relation to the immunological variants to which the kindreds belonged, namely, VII+, VIIR and VII-. Factor VII activity and antigen determinations in these subjects formed two phenotypical patterns: a discrepant pattern characterized by a low ratio activity/antigen present in VII+ heterozygotes, and a non-discrepant pattern (normal ratio activity/antigen) which is present in the VII- and VIIR variants. In the first genetic variant the detection of carriers can be performed using the ratio VII:C/VII:Ag. In the other variant, which accounts for the vast majority of heterozygotes, the distribution of the carriers' factor VII is so widespread that a large overlap results between these subjects and the normals. The application of a probabilistic calculation performed by combining the actual values of factor VII:C and the genetic probability of carriership using Fisher's linear discriminant analysis, makes discrimination between carriers and normals easier.

Impaired distribution of T-lymphocyte subsets in patients with haemophilia.

The distribution of T-lymphocyte subsets was assessed using monoclonal antibodies in 20 symptom-free patients with haemophilia. In 15 patients, the T-cell subsets appear substantially balanced with only a moderate reduction in the proportion and absolute number of OKT4 positive cells. In the remaining 5, all with a reversed OKT4/OKT8 ratio, the proportion and absolute number of OKT4 positive cells was significantly reduced (p less than 0.0002) while the absolute number of OKT8 positive cells was normal or reduced although the proportion of these cells appeared increased. Functional studies, testing the proliferative response to PHA and PWM, were normal in all cases including those with immunological abnormalities. These results suggest that a proportion of patients with classic haemophilia show some immunological abnormalities similar to those observed in patients with acquired immunodeficiency syndrome and that regular evaluation of several immunological parameters is warranted in these patients.

Studies on a family with the factor VII defect.

Investigations in a family with an isolated factor VII deficiency are reported. In one of the propositi VII Ag was reduced, in all other family members VII Ag was in the low normal range. Other investigators have observed various activation patterns of factor VII in four deficient families which were tested with thromboplastins from different sources. In contrast to most of these earlier studies the degree of activation with different thromboplastins was very similar regardless which thromboplastin was tested. These results confirm the heterogeneity of the factor VII defect. Platelet aggregation which was tested in one of the propositi with ADP, adrenaline, and collagen was found to be normal. No cold activation of factor VII was observed.

Factor VII Padua defect: the heterozygote population.

14 heterozygote patients, belonging to three families with factor VII Padua defect were investigated. All patients were asymptomatic but presented a mild prolongation of prothrombin time. Factor VII activity varied between 45 and 61% of normal and no overlap was found with the homozygous or the normal populations. On the contrary, factor VII cross-reacting material was normal. A good negative correlation was found between factor VII level and prothrombin times. All patients came from the same valley of northeastern Italy. This valley, the Piave river valley, is not far from the valley where the factor X Friuli defect was found. The significance of this peculiar geographical distribution of the two abnormalities is unknown.