AHF-like Antigen Research Articles

Detection of the Carrier State for Classic Hemophilia Using an Enzyme-Linked Immunosorbent Assay (ELISA)

A high proportion of carriers of classic hemophilia can be identified in the laboratory because, in comparison to normal women, the concentration of antigens related to antihemophilic factor (AHF, factor VIII) that are detected in their plasma by heterologous antiserum (factor VIIIR:Ag) is relatively higher than the titer of AHF that is measured in clotting assays (factor VIII:C). Enzyme-linked immunosorbent assay (ELISA) appears to overcome some of the technical difficulties associated with measurement of AHF-like antigens. The results of ELISA correlated closely with those obtained by semiquantitative immunoelectrophoresis, except in patients with von Willebrand's disease. In which ELISA appeared to provide a more quantitative estimate of AHF-like antigen. Utilizing the ELISA technique and a revised method of logarithmic discriminant analysis, we were able to distinguish all of 37 obligate carriers of hemophilia at the level of certainty that would have misclassified 5% of normal women as carriers. The relative simplicity of ELISA suggests its utility in the diagnosis of the carrier state in the female relatives of hemophiliacs.

Detection of the carrier state for classic hemophilia using an enzyme- linked immunosorbent assay (ELISA)

A high proportion of carriers of classic hemophilia can be identified in the laboratory because, in comparison to normal women, the concentration of antigens related to antihemophilic factor (AHF, factor VIII) that are detected in their plasma by heterologous antiserum (factor VIIIR:Ag) is relatively higher than the titer of AHF that is measured in clotting assays (factor VIII:C). Enzyme-linked immunosorbent assay (ELISA) appears to overcome some of the technical difficulties associated with measurement of AHF-like antigens. The results of ELISA correlated closely with those obtained by semiquantitative immunoelectrophoresis, except in patients with von Willebrand's disease. In which ELISA appeared to provide a more quantitative estimate of AHF-like antigen. Utilizing the ELISA technique and a revised method of logarithmic discriminant analysis, we were able to distinguish all of 37 obligate carriers of hemophilia at the level of certainty that would have misclassified 5% of normal women as carriers. The relative simplicity of ELISA suggests its utility in the diagnosis of the carrier state in the female relatives of hemophiliacs.

Spontaneous Haemophilia in a Genotypically Normal Female -A Family Study

The diagnosis of spontaneous haemophilia A with severe antihaemophilic globulin deficiency (less than 1%) was established in an 11-year-old girl with a normal female chromosomal pattern. Coagulation studies proved that the proposita is the offspring of a normal father with negative history for bleeding disorders and a normal mother who had an antihaemophilic globulin concentration of 200%. Family history revealed no bleeding disorder in 3 successive generations of the maternal side. This together with AHF activity exceeding slightly AHF-like antigen concentration provides good evidence against the carrier state of the mother. The possible mechanisms through which spontaneous haemophilia may occur in a genotypically normal female are discussed.

Studies on Platelet Survival and Physiological Inhibitors of Blood Coagulation and Fibrinolysis in Patients with Behcet's Disease

We have reported that the patients with Behcet's disease are generally in hypercoagulable state. The present paper concerns our investigation into the platelet survival time and the level of natural inhibitors of blood coagulation and fibrinolysis such as anti-thrombin III (AT-III), α2-macroglobulin (α2-MG), and α1-antitrypsin (α1-AT), in 23 patients with ocular manifestation of Behcet's disease. The platelet survival study was performed in 21 patients by the method of arachidonate-induced lipid peroxidation in aspirin loaded platelets and the inhibitors were measured by radial immunodiffusion technic. Seventeen of them were males and 6 were females, and their ages ranged from 18 to 52 years, 14 of whom had been treated with anticoagulant drug.The level of AT-III (28.5±4.6mg/dl) was significantly lower than in normal subjects (p<0.001). On the other hand, that of α1-AT (230.4±50.2mg/dl) was increased (p<0.001). That of α2-MG (187.0±39.2mg/dl) was slightly decreased without significance. There was no significant difference in these inhibitor levels between the patients in remission and in attack of ocular inflammatory manifestations, and anticoagulant treatment of 6 months' duration had neither significantly affected these levels.The platelet half-life (T1/2) in vivo was 3.96±0.44 days in 5 patients in attack, while it was 5.36±1.09 days in 16 patients in remission and 4.75±0.02 days in normal subjects. There was a significant shortening of platelet survival in attack stage (p<0.01), which may suggest that there is increased platelet consumption in exacerbated stage of Behcet's disease.Although there were no significant changes in the inhibitor levels and platelet half-life after administration of anticoagulant (Warfarin), anticoagulant therapy seemed to be clinically effective in 10 out of 14 patients and the increased levels of fibrinogen, AHF procoagulant activity and AHF-like antigen were normalized on Warfarin treatment.From these results the combination of oral anticoagulant and antiplatelet drugs may be more beneficial treatment for the patients with Behcet's disease.

Coagulation studies in patients with Behçet's disease, with special reference to antihemophilic factor (AHF)

Blood coagulation studies were performed on 57 occasions in 20 patients with Behcet's disease who had ocular manifestations, consisting of 15 males and 5 females from 27 to 52 years of age.ADP-induced platelet aggregation was increased on 4 occasions out of 8 in patients with exacerbated ocular inflammatory manifestations (attack), while it was increased only on 5 occasions out of 32 in patients in the stage of remission (remission). Kaolin-activated partial thromboplastin time was shortened and the levels of fibrinogen, factors V and VIII (AHF) were elevated on many occasions both in attack and remission.AHF procoagulant activity was 158.4±56.4% (Mean±SD) of normal in attack and 135.4±40.6% in remission. The level of AHF-like antigen measured by immunoelectrophoresis using rabbit antibody against human AHF was 181.9±64.4% of normal in attack and 125.6±43.8% in remission. There was a statistically significant increase in the level of AHF-like antigen in patients with attack (p<0.05). The ratio of AHF procoagulant activity to AHF-like antigen (activity/antigen) was 0.83±0.13 in attack and 1.08±0.29 in remission, and there was a significant difference between both values (p<0.05).These results suggest that the patients with this disease may generally be in hypercoagulable state and in the stage of aggravation of ocular inflammation there may be formed some microthrombi locally in the ocular venules (localized intravascular coagulation), which results in the increased production of AHF and some other clotting factors and leads to “vicious circle”.

AHF activity and AHF-like antigen in liver diseases

The procoagulant activity of antihemophilic factor (AHF-Ac) and AHF-like antigen (AHF-Ag) level in liver diseases have not been well studied, although it has already been shown that the level of vitamin K dependent clotting factors such as prothrombin, factors VII, IX and X is a very sensitive parameter of liver function.We studied AHF-Ac and AHF-Ag in 13 patients with acute hepatitis (AH), 15 with chronic active hepatitis (CAH), 20 with compensated liver cirrhosis (CLC) and 16 with decompen-sated liver cirrhosis (DCL). Also were performed coagulation studies in the same patients, such as hepaplastintest, prothrombin time, kaolin-activated PTT and assays of fibrinogen, prothrombin, factors V and IX.Hepaplastintest was normal in the majority of patients with AH, whilst many cirrhotic patients showed abnormal value. Prothrombin time and APTT were also within normal limits in the majority of cases of AH, CAH and CLC. Level of prothrombin and factor IX was proved to be a good parameter of liver function, although that of fibrinogen and factor V was insensitive to liver damage.AHF-Ac and AHF-Ag were both increased in almost all patients with the hepatic disorders mentioned above. The mean values of the AHF-Ac were 257±139% in AH, 124±53% in CAH, 104±30% in CLC and 189±74% in DLC, whilst those of AHF-Ag were 190±89%, 189±50%, 207±56% and 344±191% respectively.AHF-Ac in cirrhotic patients correlated well with serum γ-globulin level (p<0.01) and also was there close correlation between AHF-Ac and serum bilirubin level in patients with AH, but not statistically significant.The AHF-Ac/AHF-Ag ratio in patients with AH was 1.53±0.94, in contrast to 0.70±0.31 in CAH, 0.54±0. 24 in CLC and 0.63±0.27 in DLC, which showed higher level of AHF-Ac than that of AHF-Ag in AH.The cause of increased level of AHF in hepatic disorders still remains unknown, although increased extrahepatic production of AHF due to stress states and delayed inactivation and clearance of this factor in the liver may be playing a main role.

Evaluation of the detection rate of hemophilia carriers

The detection rate of hemophilia A carriers was evaluated on the basis of AHF-activity and AHF-like antigen determination. Statistical tolerance regions were constructed containing 50 and 95% of the AHF-activity and AHF-like antigen determinations of individuals of the normal or carrier group. Using these regions 18 out of 22 obligatory carriers are outside the 95% tolerance region of the normals. On the basis of AHF-activity alone only 8 out of 22 obligatory carriers are outside the 95% tolerance interval for the normals. For individual counselling for possible or potential carriers, with a prior chance (i.e. genetically determined) on carriership, the probabilities of carriership are calculated with the theorem of Bayes.

Von Willebrand病，thrombasthenia及びessential athrombiaにおける血小板のRistocetin凝集能

von Willebrand病，thrombasthenia及びessential athrombiaにおける血小板のRistocetin凝集能

Studies on atihemophilic factor (AHF, factor VIII) during labor in normal women, in patients with premature separation of the placenta, and in a patient with von Willebrand's disease

Abstract In patients with the hemorrhagic state associated with premature separation of the placenta and evidences of intravascular clotting, the titer of antihemophilic factor (AHF, factor VIII) clot-promoting activity was grossly reduced without similar depression of AHF-like antigen. Similar, but less extensive changes were observed in some, but not all women undergoing normal labor and delivery. In a patient with von Willebrand's disease, levels of clot-promoting activity and AHF-like antigen rose together during pregnancy to values normal for nonpregnant women, but the bleeding time remained prolonged even when these elevations were most pronounced just before labor.

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.

Changes in antihemophilic factor (AHF, factor 8) procoagulant activity and AHF-like antigen in normal pregnancy, and following exercise and pneumoencephalography.

Abstract Antihemophilic factor (AHF) procoagulant activity and AHF-like antigen were found to change proportionately during normal pregnancy. This proportionality may allow detection of the hemophilic carrier state during pregnancy by examination of the ratio of AHF procoagulant and antigen, AHF procoagulant activity and AHF-like antigen were also found to change proportionately following physical exercise and pneumoencephalography.

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.

Immunologic differentiation of classic hemophilia (factor 8 deficiency) and von Willebrand's dissase, 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 Willebrand's disease. The experiments described suggest that von Willebrand's 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.