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Immunological Tests for Diagnosis of Disease and Identification of Molecules
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
Another basic format for immunoassays is the competitive assay. In this assay, a competition between bound and free antigen, or labeled and unlabeled antigen, for available antibody binding sites occurs. This type of assay results in an inverse standard curve; for increasing concentrations of antigen in the sample being tested, a decrease in signal is observed.
Laboratory evaluation of thyroid function
Published in Pallavi Iyer, Herbert Chen, Thyroid and Parathyroid Disorders in Children, 2020
Immunoassays are the mainstay for measuring TSH and TH. Immunoassays rely upon a labeled antibody reacting with an analyte (such as TSH) of interest. Advantages of immunoassays include their ability to detect small amounts of analyte, lack of significant personnel oversight/participation, and quick time to result (2). As specificity of the labeled antibodies improved, so did the sensitivity of the assays. For example, the first generation TSH assays had a lower limit of detection of 1.0 mIU/L. The third generation TSH assays now have a detection of 0.01 mIU/L (1). Both biotin and streptavidin are commonly used in these immunoassays (2,4), and this will become important when considering assay interference.
Immunological Approaches
Published in Adorjan Aszalos, Modern Analysis of Antibiotics, 2020
Deborah E. Dixon, Susan J. Steiner, Stanley E. Katz
A number of nonisotopic immunoassays have been developed that avoid the problems encountered when working with radioimmunoassays. Nonisotopic immunoassays only differ from the isotopic immunoassays in terms of the type of label used, the means of end point detection, and the possibility of circumventing a separation step. There are two types of nonisotopic immunoassays: fluoroimmunoassays, which employ fluorophore-labeled antigen, and enzymoimmunoassays, in which the antigen is labeled with an enzyme [20]. These types of assays can be further subdivided, depending on whether the method requires a separation step. The nonseparation nonisotopic immunoassays include polarization fluoroimmunoassays, direct quenching fluoroimmunoassay, substrate-labeled fluoroimmunoassay, and nonseparation enzymoimmunoassay.
A comparative review of immunoassays for COVID-19 detection
Published in Expert Review of Clinical Immunology, 2021
Elham Mohit, Zahra Rostami, Hossein Vahidi
Different serological tests are accessible to determine the antibody response elicited by SARS-CoV-2 infection. The main methodologies include enzyme-linked immunosorbent assays (ELISAs), chemiluminescent immunoassays (CLIAs), lateral flow immunoassays (LFIAs) (Figure 1(a)). Furthermore, neutralization (NT) assays measure neutralizing antibodies that have the ability to effectively bind to virus and block its replication [15]. In this review, we aimed to gather the results of different validation studies related to serological tests of SARS-CoV-2 infection. Furthermore, we also compared the diagnostic performance of different methods. Accordingly, the main serological methods were described. Then, comparisons between cases in each method and comparison between different methods were explained (Figure 1(b)).
Evaluation of the diagnostic performance of an immunoblot for ANCA and anti-GBM antibody detection
Published in Autoimmunity, 2021
Matthias H. Busch, Joop P. Aendekerk, Joyce J. B. C. van Beers, Pieter van Paassen, Jan G. M. C. Damoiseaux
Advantages of the immunoassay are the rapid testing and the automated read-out for obtaining semi-quantitative results. Detection of ANCA and anti-GBM antibodies with qualitative immunoassays can lead to variations in the interpretation of the test results, as reflected by the high inter-observer effect especially for anti-GBM antibodies [13]. This can be an impairment, for instance in acute settings when experienced laboratory staff is not available. Reporting of semi-quantitative results can limit this problem and can help to improve the diagnostic accuracy as presented in our study. Finally, we observed in 4 out of 33 patients with previously negative ANCA testing a positive immunoblot for MPO-ANCA. A prospective study that evaluates whether the used immunoblot could increase the detection of ANCA autoantibodies and could allow the diagnosis of AAV in patients with previously negative ANCA testing would be interesting.
Bioidentical hormones
Published in Climacteric, 2021
F. Z. Stanczyk, H. Matharu, S. A. Winer
Since non-FDA-approved bioidentical hormone therapy (BHT) has no dose response or clinical trial data for the prescriber to consult, it is common for the compounders to combine prescribing with serum or plasma, and particularly saliva, testing of hormones to achieve a target level in the body decided by the prescriber. However, the salivary testing of sex steroid hormones so widely used by proponents of compounded BHT does not provide a unified foundation for evaluation and development due to large variability in the measurements. These variations are predominantly due to the delivery system (oral or parenteral), preparation of the saliva sample, type of assay used, and lack of standardization among assays. The assays generally use direct immunoassays, i.e. without a preceding purification step, and lack sensitivity and specificity.