Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0684275 (haemophilia)
 10,958 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have studied the conditions of in vitro binding of platelet glycoprotein IIb/IIIa (GPIIb/IIIa) to fibrinogen and applied the results to identify and measure the serum inhibitors to the binding. For the enzyme-linked immunosorbent assay, platelet extract was delivered to a fibrinogen-coated microtiter plate that was incubated for 2 hours, followed by incubation with anti-GPIIb/IIIa monoclonal antibody for another 2 hours. The plate was then incubated with peroxidase-conjugated anti-mouse IgG for color development. The binding was shown to be calcium-dependent. The binding was partially blocked by treating the coated fibrinogen with anti-fibrinogen antibody. Reduction or dissociation of GPIIb/IIIa resulted in the total loss of its ability to bind to fibrinogen. Platelet extracts of patients with hemophilia showed decreased binding (25% and 14%, compared with control platelet extract), and an extract from a patient with Glanzmann's thrombasthenia showed no binding. With the enzyme-linked immunosorbent assay we have measured serum inhibitors to GPIIb/IIIa binding to fibrinogen in 35 hemophilia A, 17 immune thrombocytopenic purpura, 22 human immunodeficiency virus-related immune thrombocytopenic purpura, and 29 systemic lupus erythematosus serum samples. In those patients with inhibition by serum, polyethylene glycol precipitation of circulating immune complexes (CICs) decreased the inhibition by the supernatants, and all the resolubilized CIC precipitates demonstrated inhibition, which indicates that CICs play a major role in the inhibition of GPIIb/IIIa binding to fibrinogen. This, then, provides evidence of CIC-mediated impaired GPIIb/IIIa binding to fibrinogen in hemophilia A, HIV-ITP, and SLE.
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PMID:Inhibition of platelet GPIIb/IIIa binding to fibrinogen by serum factors: studies of circulating immune complexes and platelet antibodies in patients with hemophilia, immune thrombocytopenic purpura, human immunodeficiency virus-related immune thrombocytopenic purpura, and systemic lupus erythematosus. 200 77

A method for the quantitation of factor VIII clotting antigen (VIII:CAg) has been developed based on a micro enzyme linked immunosorbent assay (ELISA) principle employing antibodies from two polytransfused haemophilia A patients. Solid polystyrene support bound IgG fraction of inhibitor plasma extracted VIII:CAg from normal plasma and samples. Bound VIII:CAg was detected by peroxidase labelled F(ab')2 fragment of the IgG used for solid phase. Two assays, each based on its particular inhibitor antibody, were set up. The F VIII clotting antigen in plasma of 30 healthy persons was found identical with the two VIII:CAg assays (r=0.97) and closely correlating with clotting activity (VIII:C) (r=0.84). Serum VIII:CAg was 67% (+/-14.5%) of the corresponding plasma value. In severe haemophilia A, 17 out of 19 had VIII:CAg values less than 1 U/dl. Two patients with cross-reactive material (CRM+) were found. In some milder cases of haemophilia A, higher values of VIII:CAg than VIII:C was recorded. The sensitivity of the method was 0.08 U/dl. Inter assay coefficient of variation at the 100 U/dl level was 9.5% (CV%), at the 2 U/dl level 16.4% (CV%). Mainly due to the great stability of enzyme conjugated antibody compared to the natural decay of radioiodinated material and subsequent loss of detecting material, ELISA was found superior to immunoradiometric assay (IRMA).
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PMID:Enzyme linked immunosorbent assay (ELISA) for the measurement of factor VIII coagulant antigen (CAg) using haemophilic antibodies. 308 Oct 21

Incubation of factor IX with non-precipitating alloantibodies to factor IX gives rise to soluble complexes between factor IX and the alloantibodies. These complexes appear as a factor IX molecule with a reduced mobility in crossed immunoelectrophoresis against a rabbit antiserum to factor IX. This factor IX immunoprecipitate was used for the study of alloantibodies to factor IX from five patients with severe haemophilia B (antibody titres 0.1--800 units/ml plasma). Incorporation of antiserum to k light chains or lambda light chains of human immunoglobulin G in an intermediate gel in crossed immunoelectrophoresis gave a reduction of the factor IX precipitin arc, indicating the presence of immunoglobulin G alloantibodies containing both k and lambda light chains in complex with factor IX. Incubation of the factor IX immunoprecipitate with peroxidase-conjugated antisera to the same immunoglobulins, and staining for peroxidase activity, confirmed the presence of immunoglobulin G containing both types of light chains in the factor immunoprecipitate. It is concluded that all five alloantibodies were polyclonal immunoglobulin G antibodies. The technique had the advantage that the light chain types of low-titre antibodies could be determined, and it may be suitable for further characterization of alloantibodies to factor IX if antibodies to immunoglobulin subclasses are available.
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PMID:Alloantibodies to factor IX in Haemophilia B characterized by crossed immunoelectrophoresis and enzyme-conjugated antisera to human immunoglobulins. 678 66

We have established a simple enzyme-linked immunosorbent assay (ELISA) for the detection of anti-factor IX IgG subclasses in haemophilia B patients with inhibitors. The assay was performed using immobilized purified factor IX. Specific IgG subclasses were detected by peroxidase-conjugated anti-human IgG1,2,3 and 4. Ten plasma samples from 6 haemophilia B patients with inhibitors ranging from 1.0 to 253 Bethesda Units/ml were analyzed. All samples were positive for IgG4. Six out of 10 samples were positive only for IgG4. Three samples were positive for IgG2. Five of the 6 patients had previously had allergic reactions to factor IX concentrates. Three patients had allergic episodes within the past month. Three samples from these latter patients taken on the day when the allergy had occurred showed positive also for IgG1. In later samples, however, taken at 4 days and 4 weeks respectively from two of these same patients. IgG1 was not detected. In two of the five patients in whom allergic reactions had occurred more than one month previously IgG1 was not detected. The results suggested that allergic reactions in patients with haemophilia B treated with factor IX concentrates were associated with the development of the specific IgG1 subclass of antibody to factor IX.
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PMID:Measurement of anti-factor IX IgG subclasses in haemophilia B patients who developed inhibitors with episodes of allergic reactions to factor IX concentrates. 887 Jan 72

Monoclonal antibodies (MoAbs 833 and D4H1) directed against human factor VIII (FVIII) have been produced on a large scale to measure VIII:CAg by two-site ELISA (Asserachrom VIII:CAg, Diagnostica Stago). F(ab')2 from MoAb 833 were used for coating and bound VIII:CAg was revealed with MoAb D4H1 coupled to peroxidase. Control plasma (100 VIII:CAg U dL-1 by comparing with the International Standard) was used as reference. The assay sensitivity was 0.1 U dL-1 VIII:CAg. No apparent effect of the plasma proteins was observed provided plasma dilution was > or = 5. Thus this ELISA allowed us to estimate VIII:CAg levels of 0.5 U dL-1 in plasma. Levels of VIII:CAg were similar to those of VIII:C (correlation coefficient r = 0.87) in plasma from normal individuals (32 cases) and in patients with von Willebrand disease of various types (30 cases). Among 294 patients with haemophilia A (HA), 161 had severe HA (VIII:C < 1 U dL-1). Among those patients, 124 were cross-reacting material (CRM) negative with undetectable VIII:CAg and 37 were CRM+ (VIII:CAg 1-31 U dL-1). In 42 patients with moderate HA (VIII:C 1-5 U dL-1), 33 were CRM reduced (VIII:CAg 0.5-8 U dL-1) and nine were CRM+ with a VIII:CAg/VIII:C ratio of 6-91 (mean 34.3). In mild HA (91 cases with VIII:C > or = 6 U dL-1), 29 patients were classified as CRM+ (VIII:C 6-57 U dL-1, VIII:CAg 17-130 U dL-1 and VIII:CAg/VIII:C ratio 1.8-13.7 (mean 4.51)). In 62 CRM reduced patients there was a linear correlation between VIII:C (6-39 U dL-1) and VIII:CAg (2-36 U dL-1) levels (r = 0.88). In conclusion, this sensitive assay allows us to distinguish the quantitative CRM reduced and negative from the qualitative (CRM+) abnormalities in haemophilia A.
Haemophilia 1998 Mar
PMID:Assay of factor VIII antigen (VIII:CAg) in 294 haemophilia A patients by a new commercial ELISA using monoclonal antibodies. 987 46

We tested for antibodies against factor VIII by using monoclonal antibody-purified factor VIII preparation as a source of antigen. The factor VIII was adsorbed on nitrocellulose membranes and stored in a refrigerator until later use. Plasma or serum was incubated with the factor VIII containing strip and the antibody was detected by another incubation with peroxidase-labelled antihuman immunoglobulin antibodies. The test was efficient in detecting antibodies in haemophilic and normal subjects with acquired inhibitors to factor VIII. It also detected antibodies to the factor VIII protein in a haemophilic subject with no evidence of inhibitor. The technique is simple, readily applicable, and serves as a useful screening tool for detecting factor VIII antibodies. The stability of the antigen-containing strips in a refrigerator is a practical advantage with potential commercial application.
Haemophilia 1995 Jul
PMID:A new approach to immunologic identification of factor VIII antibodies. 2721 35