Measurement Of Inhibitors To Procoagulant Factor VIII (VIIIC) By Immunoradiometric Assay (IRMA)

1981 ◽  
Author(s):  
R A Furlong ◽  
I R Peake ◽  
A L Bloom
Keyword(s):  
Factor Viii ◽  
Solid Phase ◽  
Factor Viii Inhibitor ◽  
Immunoradiometric Assay ◽  
Plasma Samples ◽  
Antigenic Sites ◽  
Increased Sensitivity ◽  
Viii Inhibitor ◽  
Dilution Curves

Antibodies against VIIIC (VIIICAg) were assayed using a modification of a two-site solid phase IRMA for factor VIII clotting antigen (VIIICAg). Anti-VIIICAg antibodies obtained from a multi- transfused haemophiliac were separated as IgG and labelled with I125. This was used to test plasma from patients with factor VIII inhibitor by competetive binding to common antigenic sites on immunoimobilised VIIIC. A haemophilic inhibitor assessed as 225u by the Bethesda method was used as standard. Results of inhibitor assay using the IRMA in 19 plasma samples from 15 severe haemophiliacs were similar to those obtained by the coagulation method. The increased sensitivity by IRMA of 0.01 u/ml enabled measurement of a haemophilic inhibitor undetectable by clotting assay. Anti VIIICAg activity was also detectable in plasmas from three individuals with acquired inhibitors against VIIIC. These plasmas which also had measurable residual VIIICAg gave dilution curves non-parallel to the standard haemophilic plasma curve. Measurement of haemophilic inhibitors using three IRMAs each employing different I125 labelled haemophilic anti VIIICAg antibodies showed that there was no difference in the sensitivity of the three assays but in some plasmas the results were discrepant indicating different specificities of the labelled antibodies.

scholarly journals Immunoblot analysis shows changes in factor VIII inhibitor chain specificity in factor VIII inhibitor patients over time

Blood ◽  
1988 ◽  
Vol 72 (4) ◽  
pp. 1348-1356 ◽  
Author(s):  
CA Fulcher ◽  
K Lechner ◽  
S de Graaf Mahoney
Keyword(s):  
Factor Viii ◽  
Heavy Chain ◽  
Immunoblot Analysis ◽  
Factor Viii Inhibitor ◽  
Plasma Samples ◽  
Anamnestic Response ◽  
Fviii Inhibitor ◽  
Viii Inhibitor ◽  
Inhibitor Patient ◽  
Over Time

Abstract We have used immunoblotting of purified factor VIII (FVIII) to determine whether or not changes in FVIII chain specificity occur during the course of an inhibitor. Serial plasma samples from 15 inhibitor patients (13 hemophilic and two spontaneous) were analyzed. Nine of the 15 antibodies, all with epitopes on the 44-kilodalton (Kd) thrombin fragment of the 92-Kd FVIII heavy chain and/or the 72-Kd thrombin fragment of the 80-Kd FVIII light chain, showed no change in FVIII chain specificity. However, six of the inhibitors analyzed showed changes in FVIII fragment specificity. Four inhibitors (three hemophilic and one spontaneous) reactive with 72-Kd thrombin fragment also became reactive with the 44-Kd thrombin fragment after an anamnestic response to FVIII infusion. Another inhibitor with epitopes on both the 54-Kd and 44-Kd thrombin fragments lost most of its reactivity with the 44-Kd fragment but retained its reactivity with the 54-Kd fragment following a FVIII infusion. The inhibitor later regained its 44-Kd-fragment reactivity but lost its 54-Kd-fragment reactivity following treatment with FEIBA, FVIII inhibitor bypassing activity. The last inhibitor studied had an antibody to either the 44-Kd fragment or to both the 44-Kd and 72-Kd fragments during anamnestic responses to FVIII. These data indicate that a FVIII inhibitor patient can potentially produce antibody to multiple areas on the FVIII molecule and that this must be taken into account in the design of specific therapeutic products.

Immunoradiometric Assay Of VIII:CAG, A Potential Tool To Detect Human Anti-VIII:C Antibodies

1981 ◽  
Author(s):  
J A Hellings ◽  
J Over ◽  
F R van Leeuwen ◽  
J A van Mourik
Keyword(s):  
Factor Viii ◽  
Solid Phase ◽  
High Titer ◽  
Test Sample ◽  
Test System ◽  
Human Antibody ◽  
Immunoradiometric Assay ◽  
Plasma Samples ◽  
Heterologous Antiserum ◽  
High Dilutions

A modification of a two-site, solid-phase immunoradiometric assay (IRMA) for Factor VIII coagulant antigen (VIII: CAg) has been evaluated for its potential to detect antibodies against Factor VIII coagulant activity (VIII: C) in patient plasma samples. For this purpose the assay system comprised four steps: 1) coating of test tubes with human anti —VIII:C , 2) incubation with normal Factor VIII— VWF complex, 3) incubation with test sample, and 4) binding of radiolabeled human anti–VIII: C as marker.Of eight hemophilic plasma samples containing antibodies against VIII: C (as detected in a clotting assay) five were able to prevent binding of radiolabel partially and three prevented this completely. One of these three (which actually was the antibody used in the IRMA), was effective even at very high dilutions. Two hemophilic plasma samples without detectable antibodies in the clotting assay, a severe Von Willebrand’s disease plasma and normal plasma samples showed no significant interference with binding of radiolabeled human anti-VIII: C. Also, a plasma sample containing a high titer of spontaneous human antibody to VIII: C as well as a heterologous antiserum against Factor VIII—VWF complex did not interfere with binding of radio-activity.It is concluded that the test system described is a sensitive tool to detect antibodies of the same specificity as those used in the IRMA. It may also detect antibodies of differing specificity. The lack of crossreactivity with some antibodies points to interindividual differences in specificity of antibodies against VIII: C.

scholarly journals Immunoblot analysis shows changes in factor VIII inhibitor chain specificity in factor VIII inhibitor patients over time

Blood ◽  
1988 ◽  
Vol 72 (4) ◽  
pp. 1348-1356 ◽  
Author(s):  
CA Fulcher ◽  
K Lechner ◽  
S de Graaf Mahoney
Keyword(s):  
Factor Viii ◽  
Heavy Chain ◽  
Immunoblot Analysis ◽  
Factor Viii Inhibitor ◽  
Plasma Samples ◽  
Anamnestic Response ◽  
Fviii Inhibitor ◽  
Viii Inhibitor ◽  
Inhibitor Patient ◽  
Over Time

We have used immunoblotting of purified factor VIII (FVIII) to determine whether or not changes in FVIII chain specificity occur during the course of an inhibitor. Serial plasma samples from 15 inhibitor patients (13 hemophilic and two spontaneous) were analyzed. Nine of the 15 antibodies, all with epitopes on the 44-kilodalton (Kd) thrombin fragment of the 92-Kd FVIII heavy chain and/or the 72-Kd thrombin fragment of the 80-Kd FVIII light chain, showed no change in FVIII chain specificity. However, six of the inhibitors analyzed showed changes in FVIII fragment specificity. Four inhibitors (three hemophilic and one spontaneous) reactive with 72-Kd thrombin fragment also became reactive with the 44-Kd thrombin fragment after an anamnestic response to FVIII infusion. Another inhibitor with epitopes on both the 54-Kd and 44-Kd thrombin fragments lost most of its reactivity with the 44-Kd fragment but retained its reactivity with the 54-Kd fragment following a FVIII infusion. The inhibitor later regained its 44-Kd-fragment reactivity but lost its 54-Kd-fragment reactivity following treatment with FEIBA, FVIII inhibitor bypassing activity. The last inhibitor studied had an antibody to either the 44-Kd fragment or to both the 44-Kd and 72-Kd fragments during anamnestic responses to FVIII. These data indicate that a FVIII inhibitor patient can potentially produce antibody to multiple areas on the FVIII molecule and that this must be taken into account in the design of specific therapeutic products.

Acquired Haemophilia: Functional Study of Antibodies to Factor VIII

1981 ◽  
Vol 45 (03) ◽  
pp. 285-289 ◽  
Author(s):  
J P Allain ◽  
A Gaillandre ◽  
D Frommel
Keyword(s):  
Factor Viii ◽  
Functional Study ◽  
Factor Viii Inhibitor ◽  
Acquired Haemophilia ◽  
Viii Inhibitor ◽  
Kinetics Of ◽  
Antibody Function ◽  
Native Plasma

SummaryFactor VIII complex and its interaction with antibodies to factor VIII have been studied in 17 non-haemophilic patients with factor VIII inhibitor. Low VIII:C and high VIIIR.Ag levels were found in all patients. VIII:WF levels were 50% of those of VTIIRrAg, possibly related to an increase of poorly aggregated and electrophoretically fast moving VIIIR:Ag oligomers.Antibody function has been characterized by kinetics of VIII :C inactivation, saturability by normal plasma and the slope of the affinity curve. Two major patterns were observed:1) Antibodies from 6 patients behaved similarly to those from haemophiliacs by showing second order inhibition kinetics, easy saturability and steep affinity slope (> 1).2) Antibodies from other patients, usually with lower titres, inactivated VIII :C according to complex order kinetics, were not saturable, and had a less steep affinity slope (< 0.7). In native plasma, or after mixing with factor VIII concentrate, antibodies of the second group did not form immune complexes with the whole factor VIII molecular complex. However, dissociation procedures did release some antibodies from apparently low molecular weight complexes formed in vivo or in vitro. For appropriate management of non-haemophilic patients with factor VIII inhibitor, it is important to determine the functional properties of their antibodies to factor VIII.

A Higher than Expected Incidence of Factor VIII Inhibitors in Multitransfused Haemophilia A Patients Treated with an Intermediate Purity Pasteurized Factor VIII Concentrate

1993 ◽  
Vol 69 (02) ◽  
pp. 115-118 ◽  
Author(s):  
Kathelijne Peerlinck ◽  
Jef Arnout ◽  
Jean Guy Gilles ◽  
Jean-Marie Saint-Remy ◽  
Jos Vermylen
Keyword(s):  
Factor Viii ◽  
Randomized Trials ◽  
Specific Factor ◽  
Factor Viii Inhibitor ◽  
Haemophilia A ◽  
Viral Inactivation ◽  
Gradual Decline ◽  
Inhibitor Level ◽  
Factor Viii Concentrates ◽  
Viii Inhibitor

SummaryIn May 1990, 218 patients with haemophilia A regularly attending the Leuven Haemophilia Center were randomly assigned to a group receiving either of two newly introduced factor VIII concentrates: factor VIII-P, an intermediate purity pasteurized concentrate, or factor VIII-SD, a high purity concentrate treated with solvent-detergent for viral inactivation.Patients were followed from May 1990 until October 1991. Between August 1991 and October 1991 a clinically important factor VIII inhibitor was detected in five out of the 109 patients receiving factor VIII-P while none of the 109 patients receiving factor VIII-SD developed such antibodies. All patients acquiring an inhibitor had previously been clinically tolerant to transfused factor VIII with 200 to more than 1,000 days of exposure to factor VIII prior to May 1990. Patients with inhibitors were transfused daily with 30 U factor VIII-SD per kg body weight, which was associated with a gradual decline of the inhibitor level. In all patients the antibodies were relatively slow-acting and predominantly directed towards the light chain of factor VIII.This study demonstrates a higher than expected incidence of factor VIII inhibitors associated with the use of a specific factor VIII concentrate in multitransfused haemophilia A patients. It indicates the usefulness of evaluating newly introduced concentrates in prospective, randomized trials.

In Vitro Thrombogenicity Tests of Factor IX Concentrates

1979 ◽  
Vol 42 (05) ◽  
pp. 1355-1367 ◽  
Author(s):  
C V Prowse ◽  
A Chirnside ◽  
R A Elton
Keyword(s):  
Factor Viii ◽  
Partial Thromboplastin Time ◽  
Generation Time ◽  
Activated Partial Thromboplastin Time ◽  
Factor Ix ◽  
In Vitro Tests ◽  
Factor Viii Inhibitor ◽  
Factor Ixa ◽  
Viii Inhibitor

SummaryVarious factor IX concentrates have been examined in a number of in vitro tests of thrombogenicity. The results suggest that some tests are superfluous as in concentrates with activity in any of these tests activation is revealed by a combination of the non-activated partial thromboplastin time, the thrombin (or Xa) generation time and factor VIII inhibitor bypassing activity tests. Assay of individual coagulant enzymes revealed that most concentrates contained more factor IXa than Xa. However only a small number of concentrates, chiefly those that had been purposefully activated, contained appreciable amounts of either enzyme.

Pemphigus Vulgaris Associated with Acquired Hemophilia due to Factor VIII Inhibitor

2003 ◽  
Vol 65 (3) ◽  
pp. 223-226 ◽  
Author(s):  
Masahide YAMAGUCHI ◽  
Mamoru KOHDA ◽  
Hiroaki UEKI ◽  
Wataru FUJIMOTO
Keyword(s):  
Factor Viii ◽  
Pemphigus Vulgaris ◽  
Factor Viii Inhibitor ◽  
Acquired Hemophilia ◽  
Viii Inhibitor

Factor-VIII Inhibitor in Less Severely Affected Haemophilic Patients

1975 ◽  
Author(s):  
E. G. D. Tuddenham ◽  
A. L. Bloom ◽  
J. C. Giddings ◽  
C. A. Barrett
Keyword(s):  
Factor Viii ◽  
Factor Viii Inhibitor ◽  
Factor Viii Level ◽  
Replacement Treatment ◽  
Viii Level ◽  
Viii Inhibitor ◽  
In Vivo Recovery ◽  
Better Than

The occurrence of factor VIII inhibitor in five mild or moderately affected liaemophilic patients is described. In four patients the inhibitor inactivated endogenous factor VIII an dtemporarily converted them to severely affected haemophiliacs with factor VIII level of 0%. In the fifth patient, a brother of one of the others, the inhibitor although more potent did not inactivate the patient’s own factor VIII and did not completely inactivate normal factor VIII in vitro. This patient responded to treatment with factor-VIII concentrate but the in-vivo recovery was reduced. The patient’s plasma was tested against a panel of normal donors but it inactivated factor VIII in each to a similar extent and no evidence for normal factor-VIII groups was obtained. In the other patients the response to replacement treatment was also better than that usually seen in severely affected haemophilic patients with inhibitor. In the two related patients the inhibitors have so far persisted but in the unrelated patients the inhibitors eventually disappeared and did not always recur with subsequent therapy. The incidence of factor- VIII inhibitor in less severe haemophiliacs (factor VIII > 3% ) in this centre is 6% suggesting that the complication is more frequent in this type of patient than hitherto recognised.

scholarly journals A Clinical and Experimental Study of Acquired Inhibitors to Factor VIII

Blood ◽  
1965 ◽  
Vol 26 (6) ◽  
pp. 805-818 ◽  
Author(s):  
HAROLD R. ROBERTS ◽  
MARGARET B. SCALES ◽  
JOHN T. MADISON ◽  
WILLIAM P. WEBSTER ◽  
GEORGE D. PENICK
Keyword(s):  
Experimental Study ◽  
Factor Viii ◽  
Mode Of Action ◽  
Exchange Transfusion ◽  
Hemophilia A ◽  
Retroperitoneal Hematoma ◽  
Factor Viii Inhibitor ◽  
Viii Inhibitor ◽  
Potent Factor

Abstract Factor VIII inhibitors which developed in four patients with hemophilia A are described. These inhibitors are apparently specific for Factor VIII and are capable of inducing a transient hemophilic state when injected into dogs. The genesis, properties, and mode of action of these inhibitors can be explained on an immunologic basis and it seems most likely that they represent an antibody to Factor VIII. One hemophilia A patient, with retroperitoneal hematoma and a potent Factor VIII inhibitor, was successfully treated by an exchange transfusion followed by administration of purified porcine Factor VIII.

Sign in / Sign up

Export Citation Format

Share Document