Use of monoclonal antibodies in an enzyme immunoassay for factor VIII-related antigen.

1984 ◽  
Vol 30 (1) ◽  
pp. 87-92 ◽  
Author(s):  
L A Bradley ◽  
E L Franco ◽  
H M Reisner
Keyword(s):  
Monoclonal Antibodies ◽  
Factor Viii ◽  
Solid Phase ◽  
Mammalian Species ◽  
Test Sample ◽  
Inhibitory Effect ◽  
Enzyme Linked Immunosorbent Assay ◽  
Response Curves ◽  
Factor Viii Related Antigen ◽  
Assay Precision

Abstract Two monoclonal antibodies (MAb 53, MAb D7) were produced, each having specificity for Factor VIII-related antigen (FVIIIR:Ag), but exhibiting no inhibitory effect on either procoagulant activity or the ability of von Willebrand factor to agglutinate platelets in the presence of the antibiotic ristocetin. For quantification of FVIIIR:Ag, we used the antibodies in a competitive enzyme-linked immunosorbent assay (ELISA). Binding of either of the MAb's to solid-phase antigen was inhibited by free FVIIIR:Ag in the test sample. Dose-response curves for the reference standards were consistently linear (r2 greater than 0.990) and reproducible. The normal range of FVIIIR:Ag detected in plasma (normal defined as 1000 units/L) was similar to that reported for polyclonal heterologous antibodies in similar ELISA or immunoradiometric (IRMA) systems, and the assay was sensitive to 10 units of FVIIIR:Ag per liter. Inter- and intra-assay precision was good, coefficients of variation being less than 11%. Studies on patients showed good correlations between values measured by MAb ELISAS and IRMA (polyclonal rabbit antibody) over FVIIIR:Ag concentrations ranging from less than 10 to 2700 units/L (r = 0.971, p less than 0.001 for MAb 53; r = 0.938, p less than 0.001 for MAb D7). Both ELISAS could be used to quantify FVIIIR:Ag in other mammalian species. The assay is inexpensive and simple, and all reagents required for it are commercially available.

Enzyme immunoassay for factor VIII-related antigen.

1982 ◽  
Vol 28 (6) ◽  
pp. 1356-1358 ◽  
Author(s):  
J Cejka
Keyword(s):  
Regression Analysis ◽  
Factor Viii ◽  
Enzyme Immunoassay ◽  
Immunosorbent Assay ◽  
Present Method ◽  
Solid Phase ◽  
Enzyme Linked Immunosorbent Assay ◽  
Plasma Samples ◽  
Factor Viii Related Antigen ◽  
Elisa Technique

Abstract I describe a simple enzyme-linked immunosorbent assay (ELISA) for the quantitation of Factor VIII-related antigen in plasma with use of commercially available peroxidase-labeled antiserum and solid-phase support. Regression analysis of 85 plasma samples analyzed by this technique (y) and by a commonly used electroimmunoassay (Anal. Biochem. 15: 45-52, 1966) (x) gave the equation y = 0.223 + 0.77x (r = 0.973). The present method was also compared with enzyme immunoassay in which a phosphatase-labeled antiserum prepared in our laboratory was used; the correlation between the two assays was very good. The simplicity and specificity of the ELISA technique should make it a useful alternative to the more difficult and time-consuming Laurell method.

The Effect Of Coagulation On The Association Of VIII:CAg With VIIIR:Ag

1981 ◽  
Author(s):  
J A van Mourik ◽  
P H G Lantinga ◽  
J A Hellings
Keyword(s):  
Factor Viii ◽  
Whole Blood ◽  
Calcium Concentration ◽  
Solid Phase ◽  
Binding Capacity ◽  
The Other ◽  
Void Volume ◽  
Concomitant Increase ◽  
Initial Value ◽  
Factor Viii Related Antigen

Solid-phase immunoradiometric assays specific for Factor VIII coagulant antigen (VIII:CAg) and Factor VIII related antigen (VIIIR:Ag) have been used to assay the immunoreactivity of these antigens in plasma and whole blood during coagulation at physiological calcium concentration. When non-anticoagulated plasma, prepared from blood immediately after venipuncture, was incubated at 37°C, the concentration of VIII:CAg and VIlIR:Ag did not change. However, when whole blood, collected withoutanticoagulant, was incubated, the concentration of VIII:CAg gradually decreased to 50% of the initial value whereas the concentration of VIIIR:Ag remained unchanged. Gelchromatographic analyses revealed that coagulation of plasma leads to progressive dissociation of VIII:CAg from the factor VIII:VWF complex. When plasma was chromatographed before the onset of coagulation, VIII:CAg was eluted at the void volume together with VIIIR:Ag whereas after coagulation of the plasma VIII:CAg devoid of VIIIR:Ag was eluted after the void volume. Similarly, when the supernatant plasma from blood was chromatographed before the onset of coagulation, VIII:CAg together with VIIIR:Ag was eluted at the void volume whereas during and after coagulation the amount of VIII:CAg associated with VIIIR:Ag gradually decreased. However, no concomitant increase of the concentration of dissociated VIII:CAg was noted under the latter conditions. It seems likely, therefore, that adherance of dissociated VIII:CAg to cellular constituents accounts for the loss of VIII:CAg during coagulation of blood. On the other hand, it can not be excluded that cellular enzymes, extruded during coagulation, affect the antibody-binding capacity of VIII:CAg.Further studies indicate that, at least in part, dissociation of the factor VIII:VWF complex during coagulation is mediated by thrombin.

STUDY OF IIA VON WILLEBRAND'S DISEASE (VWD) VARIANTS TO DETERMINE DEGREE AND TYPES OF HETEROGENEITY

1987 ◽  
Author(s):  
S M Enayat ◽  
F G H Hill ◽  
Y Sultan ◽  
C W Williams
Keyword(s):  
Monoclonal Antibodies ◽  
Factor Viii ◽  
Structure Function ◽  
Gel Electrophoresis ◽  
Agarose Gels ◽  
Factor Viii Related Antigen ◽  
The Third ◽  
Edta Plasma ◽  
Abnormal Pattern ◽  
The Common

Thirty four IIA vWD patients (16 from kindred I, 2 from kindred II and 17 unrelated patients) from 19 families were studied to compare multimer patterns using discontinuous SDS gel electrophoresis on a variety of agarose gels. Platelet multi-mers and effect of EDTA on plasma multimers were also studied in some.The large kindred and 9 other patients showed identical multimer and triplet abnormalities. The 11 other patients showed different multimer patterns either by having intermediate multimers or different triplet patterns. The second kindred had a similar triplet abnormality to kindred I but had intermediate multimers. Two other patients showed similar patterns except on 2% agarose gels when differences in the lowest multimer was seen. Of the 3 patients of YS, one showed the common IIA pattern but also had intermediate multimers, another had an unusually faint upper triplet band, while the third in addition to a faint upper triplet band with ESVWF 2+ had no identification of minor or major bands with ESVWF 10+ Another patient lacked high and some intermediate multimers but had a normal triplet pattern. The pattern we have seen in Kernoff's patient (1) still appears unique. In kindred II abnormal triplets persisted and high multimers appeared in EDTA plasma. In kindred I (and similar patients) intermediate multimers and a change in triplet pattern was observed in EDTA while lysed platelets showed an abnormal pattern different to the plasma one.This emphasizes the heterogeneity of IIA vWD and the need to consider multimer deletion, triplet pattern, platelet multimers, effect of EDTA in trying to subclassify in order to study structure function relationships of vWF.1. Kernoff PBA, Gruson R, Rizza CR. (1974) A variant of factor VIII related antigen. Br. J. Haematol. 26: 435.+ESVWF 2 and 10 are monoclonal antibodies to vWF epitopes.

Inhibition of Human Platelet Aggregation by the Proteolytic Effect of Streptokinase (SK). Role of the Factor VIII Related Antigen

1975 ◽  
Author(s):  
R. Castillo ◽  
S. Maragall ◽  
J. A. Guisasola ◽  
F. Casals ◽  
C. Ruiz ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Factor Viii ◽  
Platelet Rich Plasma ◽  
Gel Filtration ◽  
Inhibitory Effect ◽  
Factor Viii Related Antigen ◽  
Human Factor Viii ◽  
Induced Aggregation

Defective ADP-induced platelet aggregation has been observed in patients treated with streptokinase. This same effect appears “in vitro” when adding SK to platelet rich plasma (PRP). Classic hemophilia and normal platelet poor plasmas (PPP) treated with SK inhibit the aggregation of washed platelets; plasmin-treated normal human serum also shows an inhibitory effect on platelet aggregation. However, von Willebrand SK-treated plasmas do not inhibit the aggregation of washed platelets. The same results appear when plasmas are previously treated with a rabbit antibody to human factor VIII.This confirms that the antiaggregating effect is mainly linked to the digested factor VIII related antigen.The inhibition of ADP-induced platelet aggregation has been proved in gel filtration-isolated and washed platelets from SK-treated PRP.Defective ristocetin-induced platelet aggregation has also been observed- This action does not appear in washed platelets from SK-treated PRP in presence of normal PPP, but it does in presence of SK-treated PPP, which suggests that the inhibition of the ristocetin-induced aggregation is due to the lack of factor VIII and not to the factor VIII-related products.Heparin, either “in vivo” or “in vitro”, has corrected the antiaggregating effect of SK.

scholarly journals Identification of functionally distinct domains of human granulocyte- macrophage colony-stimulating factor using monoclonal antibodies

Blood ◽  
1991 ◽  
Vol 77 (5) ◽  
pp. 1033-1043 ◽  
Author(s):  
Y Kanakura ◽  
SA Cannistra ◽  
CB Brown ◽  
M Nakamura ◽  
GF Seelig ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Neutralizing Antibodies ◽  
Solid Phase ◽  
Receptor Interaction ◽  
Enzyme Linked Immunosorbent Assay ◽  
Colony Stimulating Factor ◽  
Gm Csf ◽  
Macrophage Colony Stimulating Factor ◽  
Macrophage Colony ◽  
Stimulating Factor

Abstract Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a glycoprotein that is required for the survival, growth, and differentiation of hematopoietic progenitor cells. Although the primary structure of GM-CSF is known from cDNA cloning, the relationship between structure and function of GM-CSF is not fully understood. Fifteen different monoclonal antibodies (MoAbs) to human GM-CSF were generated to map immunologically distinct areas of the molecule. Each of the MoAbs was biotinylated and shown by enzyme-linked immunosorbent assay to bind to recombinant GM-CSF that had been affixed to a solid phase. Each of the 15 unconjugated MoAbs was then used to compete with each biotinylated MoAb for binding to GM-CSF. These cross-blocking studies identified eight distinct epitopes of native GM-CSF. Seven of these epitopes were also present in denatured GM-CSF by Western blotting, and four of the epitopes were at least partially conserved on GM-CSF that was reduced in beta-mercaptoethanol. MoAbs to four of eight epitopes neutralized both recombinant (glycosylated and nonglycosylated) and natural human GM-CSF in a GM colony-forming unit (CFU-GM) assay and blocked GM-CSF-induced activation of neutrophils. For most of the antibodies there was a good correlation between neutralizing activity and the capacity to block binding of 125I-GM-CSF to neutrophils or blasts. Non-neutralizing antibodies to one epitope partially blocked binding of 125I-GM-CSF to neutrophils. None of the MoAbs neutralized interleukin-3, G-CSF, or M-CSF. The locations of seven of the epitopes could be partially mapped with regard to the amino acid structure by determining reactivity to GM-CSF synthetic peptides or to human-mouse chimeric GM-CSFs. The neutralizing antibodies were found to map to amino acids 40–77, 78–94, or 110–127. Thus, these MoAbs are useful to identify functional domains of GM-CSF and in identifying regions that are likely to be involved in receptor interaction.

scholarly journals An enzyme-linked immunosorbent assay for erythropoietin using monoclonal antibodies, tetrameric immune complexes, and substrate amplification

Blood ◽  
1989 ◽  
Vol 74 (2) ◽  
pp. 622-628 ◽  
Author(s):  
AW Wognum ◽  
PM Lansdorp ◽  
AC Eaves ◽  
G Krystal
Keyword(s):  
Monoclonal Antibodies ◽  
Immunosorbent Assay ◽  
Biological Fluids ◽  
Normal Serum ◽  
Detection Sensitivity ◽  
Enzyme Linked Immunosorbent Assay ◽  
Response Curves ◽  
Human Erythropoietin ◽  
Healthy Donors ◽  
Noncovalent Labeling

We recently reported the development of several monoclonal antibodies (MoAbs) to native human erythropoietin (Ep). In the present study we have used the two antibodies with highest affinity to develop a two- sided or sandwich enzyme-linked immunosorbent assay (ELISA) to measure Ep in human serum. In this assay Ep is incubated in microtiter wells precoated with the first (IgE) anti-Ep antibody. Assay wells are then incubated with the second (IgG1) anti-Ep antibody, which is labeled noncovalently with the enzyme alkaline phosphatase (AP) by means of bispecific tetrameric antibody complexes consisting of IgG1 anti-Ep cross-linked to IgG1 anti-AP using rat MoAbs specific for mouse IgG1. Application of this noncovalent labeling procedure, in combination with substrate amplification, results in a detection sensitivity of 0.5 to 1.0 mU/sample (5 to 10 mU/mL), which makes this assay suitable for measuring normal serum Ep levels. The validity of this ELISA for quantitating Ep in biological fluids was demonstrated by the parallelism obtained between pure recombinant Ep dose-response curves and those obtained with plasma and serum from healthy donors and patients with various hematologic disorders. Normal plasma Ep levels detected with this ELISA ranged from 9 to 101 mU/mL with a mean of 32 +/- 23 (SD) mU/mL. Ep levels in sera from patients with polycythemia vera were in the low to normal range, whereas Ep levels in sera from patients with secondary polycythemia and patients with aplastic anemia were moderately to strongly elevated. These results demonstrate that the Ep-ELISA is a sensitive, reliable, and nonradioactive immunologic method for quantitating Ep levels and should prove useful in a variety of clinical and laboratory settings.

Characterization of Four Monoclonal Antibodies to Factor VIII Coagulant Protein and Their Use in Immunopurification of Factor VIII

1986 ◽  
Vol 56 (03) ◽  
pp. 271-276 ◽  
Author(s):  
Marie-Pascale Croissant ◽  
Hendrik vande Pol ◽  
Helen H Lee ◽  
Jean-Pierre Allain
Keyword(s):  
Monoclonal Antibodies ◽  
Liquid Phase ◽  
Factor Viii ◽  
Ascitic Fluid ◽  
Specific Activity ◽  
Solid Phase ◽  
Functional Impact ◽  
Affinity Constants ◽  
Normal Plasma

SummaryFour monoclonal anti-VIII: C antibodies were obtained from the fusion of the splenocytes of one B alb/C mouse with a specific activity ranging from 2.3 to 45,000 U/mg when purified from ascitic fluid. Only one antibody was able to inhibit completely Factor VIII: C in normal plasma. The four antibodies could bind Factor VIII: CAg in plasma and commercial concentrate both in liquid and solid phase, and were suitable for immunopurification of Factor VIII :C.Three antibodies competed with polyclonal anti-VIII: CAg Fab′ in a liquid phase IRMA, and all of them were able to displace their own binding to Factor VIII: CAg. Competition studies between monoclonal antibodies for the binding to Factor VIII: CAg were performed and showed the recognition of different epitopes and various functional impact. These studies indicate that at least one antibody, with the lowest anti-VIII:C titer clearly recognizes a different epitope of VIII: C than those recognized by the others. Affinity constants ranged from 109 to 1010 l/mole.

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