Electroimmunoassay

Electroimmunoassay (rocket electrophoresis) and radial immunodiffusion (A5) lack sensitivity at low Lp(a) concentrations, and the response is influenced by the size of the apo(a) isoforms (A5, K28). Differences in migration velocity in the agarose gel lead to an underestimation of the samples with large apo(a) isoforms and to an overestimation of samples with small apo(a) isoforms. Moreover, the detection limit lies around 0.07-0.08 g/liter Lp(a), so that this method is better suited for screening and detection of individuals with elevated Lp(a) levels than for the exact measurement of the plasma Lp(a) concentration. 

Abbreviations RIA, radioimmunoassay ELISA, enzyme-linked immunoassay NIA, nephelometric immunoassay TIA, turbidimetric immunoassay EIA, electroimmunoassay RID, radial im-munodiffusion. 

Data are expressed as percentages of users for each assay. Abbreviations ELISA, enzyme-linked immunosorbent assay EIA, electroimmunoassay RIA, radioimmunoassay TIA, turbidimetric immunoassay. Delfia, time resolved immunofluorescence assay. 

Although it is possible to estimate apoC concentrations in lipoprotein fractions by delipidation, electrophoresis or isoelectric focusing, staining, and densitometry [e.g., (C5, N3)], or by high-pressure liquid chromatography (H6), most reported measurements of plasma apoC concentration have been by immunological means. These include radioimmunoassay (K8, K9, S17), electroimmunoassay (A4, A5, C27), radial immunodiffusion (P21), and enzyme immunoassay (H29). 

The concentration of apoD in human serum has been reported as 10-12 mg/dl by electroimmunoassay and radial immunodiffusion (C25) and a little less (6.2 1.0 mg/dl for males, 5.6 1.4 mg/dl for females) by radial immunodiffusion (A 14). In the latter study, apoD was significantly correlated with HDL cholesterol levels in both sexes (A14). 

A5. Alaupovic, P., Curry, M., McConathy, W., and Fesmire, J., Electroimmunoassay of apolipoproteins occurring in high density lipoproteins of human plasma. In Report of the High Density Lipoprotein Methodology Workshop (K. Lippel, ed.), pp. 227-240. U.S. Department of Health, Education and Welfare. NIH publication No. 79-1661, Bethesda, Md., 1979. 

C25. Curry, M. D., McConathy, W. J., and Alaupovic, P., Quantitative determination of human apolipoprotein D by electroimmunoassay and radial immunodiffusion. Biochim. Biophys. Acta 491, 232-241 (1977). 

A number of immunochemical techniques have been used to quantify analytes of clinical interest. They include radial diffusion (RID) and electroimmunoassays, turbidimetric and nephelometric assays, and labeled immunochemical assays. 

Laurell CB. Electroimmunoassay. Scand J Clin Lab Invest 1972 29(Suppl 124) 21-37. 

Cystatin C has been measured by immunodiffusion or rocket electroimmunoassay, but the methods are too insensitive, and any form of labeled immunometric assay is too cumbersome and time consuming for the response time required. The most practical approaches described are to use a latex particle-enhanced turbidimetric or nephelometric immunoassay. An intraassay precision of less than 3% can be expected at the upper limit of the reference interval ( 1.00mg/L), with less than 4% for the between-day value. Further, cystatin C measurement appears unaffected by the spectral interferences affecting creatinine assays. ... 

Serum contains more than 100 different proteins, each under separate genetic control. They are transport proteins for hormones, vitamins, lipids, metals, pigments, and drugs enzymes enzyme inhibitors (proteinase inhibitors) hormones antibodies clotting factors complement components and kinin precursors. Quantitation (by radial immunodiffusion, electroimmunoassay, nephelometric methods, enzyme-linked immunological methods, and radioimmunoassay) of the various constituents of serum is of value in diagnosing and following the course of certain diseases. Several of these proteins are discussed elsewhere in the text. 

Electroimmunoassay, immunoradiometric assay, or enyzme-linked immunosorbent assay can be used to quantify vWF Ag. Because vWF Ag levels are known to vary with different ABO blood types, interpretation requires reference to values specific for the patient s blood type. The vWF Ag level is usually low in types 1 and 2 von Willebrand disease and virtually absent in type 3 disease. Factor VIII levels are normal or mildly decreased in patients with type 1 or 2 disease and very low (<10%) in those with type 3 disease. Ristocetin, an antibiotic that causes platelet aggregation in the presence of functional von Willebrand factor, is used to measure von Willebrand factor activity. The assay is performed by mixing platelet-free patient plasma, normal formalin-fixed platelets, and ristocetin. 

A standard curve can be constructed from dilutions of purified superoxide dismutase. The detection Umit is 0.1 ng enzyme. The method is practicable in crude homogenates, like extracts of the red blood cell. The work with radioactive tracers, however, has some disadvantages. If the highly sensitive detection limit is not required, the classical electroimmunoassay can be used. 

Fig. 11. Electroimmunoassay for human Cu Zn superoxide dismutase. Electrophoresis was carried out in the presence of antibodies against SOD. Loops 1 to 5 standards loops 6 and 7 unknown samples. (With permission from Ref. )...

Gel procedures originate from the classical immunoelectrophoresis of P. Grabar, often referred to as lEA, an abbreviation for immunoelectrophoretic analysis, and from the crossing diagrams of K. Nakamura. A distinction may be made between the two-dimensional QE of Clarke and Freeman (Figure 1) and the one-dimensional rocket immunoelectrophoresis of Laurell, often referred to as electroimmunoassay (EIA). Numerous technical modifications of these methods have been devised in order to obtain a certain characterization of one or more proteins. The methods are suitable for establishing an inventory of proteins and for molecular characterization of... 

Radial immunodiffusion and electroimmunoassay (El) Typically, the two most commonly encountered... 

Curry MD, McConathy WJ, Fesmire JD, Alaupovic P (1980) Quantitative determination of human apolipoprotein C-III by electroimmunoassay. Biochim Biophys Acta 617 503-513... 

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