Detection of tissue structures, antibodies, and pathogens by immunolabeling is popular, modern, and accurate. Immunofluorescence refers to immunolabeling with prepared fluorescent antibodies that are made to glow under UV light. In direct immunofluorescence detection, the test substrate is examined directly with luminescent antibodies, without upstream primary antibodies or artificial antigens.
What is immunofluorescence direct detection?
Tumor-specific antigens in tumor tissue can be detected directly with immunofluorescence. Thus, it is possible to find out where in the body the existing metastases came from. Immunofluorescence direct detection is a diagnostic method based on findings in immunology, immunostaining and immunohistochemistry. The focus here is on the ability of antibodies to bind to specific sites in tissue or on antigens in a serum. These sites are epitopes. In biochemical diagnostics, there are artificial antibodies or mimetics (singular: mimetic) that allow labeling of these antibody-antigen bonds by fluorescence or radioactivity. Artificial antibody conjugates in fact bind to the epitopes on the one hand and have a fluorescent marker in case of immunofluorescence on the other hand. This is an alternative to the use of radioactive markers. The special feature of immunofluorescence direct detections compared to indirect detections is that the antibody that binds to the epitope of the antigen in the examined material is at the same time already the antibody conjugate with the fluorescent marker. Additional antibodies for interposition are not necessary for direct detection. In immunofluorescence, fluorescein, which glows under UV light, and fluorescein isothiocyanate (FITC) are used as dyes to construct the artificial antibody conjugates. As far as it reads a bit complicated, but immunofluorescence direct detections are standard methods of medical laboratory diagnostics for numerous different medical issues. Antibodies containing the fluorescent dye are available ready for sale.
Function, effect, and targets
Immunofluorescence direct detectors are available for tissue studies to stain specific structures in tissue. But they also exist for single cells. That’s where flow cytometry plays a big role. And finally, there are the immunoassays consisting of solid and liquid phases. Immunofluorescence studies of tissues are important above all in oncology, i.e. the medical treatment of cancer. Tumor-specific antigens in tumor tissue can be detected directly with immunofluorescence. These examinations of tissue samples from tumors are often important for finding out where in the body the existing metastases have come from, or also for forming a judgment as to whether a tumor is benign or malignant. The examination of individual cells with immunofluorescence direct detection is used to find viral antigens, bacterial antigens and other epitopes. For example, one learns whether the cells are infected by a virus and at what stage of the infection cycle the cells are. FACS (=Fluorescence-Activated Cell Sorting) is a highly efficient flow cytometry method in which fluorescently labeled cells are distributed to different test tubes depending on the staining type. This method is important in immunology, hematology and infectiology. Immunofluorescence immunoassays allow direct detection of environmental toxins, genetically modified organisms and certain additives in food. In this experimental setup, there is always a solid and a liquid phase. Numerous pathogens, including the AIDS-causing HI virus, could also be detected directly. However, when detecting infectious and autoimmune diseases, the aim is often to detect antibodies rather than antigens. These are the defense molecules produced by the body’s own immune system. Such detections are then not direct detections according to the definition presented here, since the fluorescent antibodies do not couple directly to the body’s own antigens, but to the antigens of the test assembly. These antigens of the experimental assembly in turn link to the endogenous antibodies.Only in special detection and confirmation tests are immunofluorescence direct detections used for common infections, for example by HI viruses and Chlamydia. There are tests for many other diseases. In most situations, indirect detection of antibodies is better for infectious diseases because the body’s immune system has an ingenious ability to remember previous infections. In other situations, direct detection of antigens and indirect detection of antibodies complement each other. The latter show that an infection has occurred before, whereas the former provide more accurate information about the current status of pathogen activity.
Risks, side effects, and hazards
With immunofluorescence direct detection, as with all medical detection, come two risks: The risk of a false positive result and the risk of a false negative result. False positive results cause psychological discomfort and very great distress to the patient. Therefore, additional testing procedures are added to positive results, especially when the diagnosis leads to drastic life changes. The danger of a false negative result is that the patient does not learn in time about the threat to his own health and perhaps even to public health. Therefore, it is good to do a lot of research and make a large number of different immunofluorescence direct detections ready for sale and offer them. Together with other direct and indirect detection methods of diseases and pathologies, this increases the accuracy of diagnosis. Direct detections are based on the antibody conjugate, which on the one hand binds to the epitopes of the antigens and on the other hand also causes the fluorescence at the same time. Such a product is therefore only used in one type of test procedure and is not used for other types of tests. This is an important, procedural difference from indirect detection, in which primary antibodies are used upstream of the fluorescent antibodies for epitope binding. The antibody conjugate is thus suitable for different assays. This procedural difference is distinct from the medical difference between indirect detection of antibodies and direct detection of antigens.
