What is an immunoassay?
An immunoassay is a type of laboratory test that uses the principles of immunology to detect the presence or concentration of a specific substance in a sample. This type of assay typically involves the use of antibodies, which are proteins produced by the immune system in response to the presence of a specific substance (known as an antigen). The antibodies are highly specific, meaning that they will only react with the specific antigen they were produced against.
Different types of assays
There are several different types of immunoassays, including:
- Enzyme-linked immunosorbent assay (ELISA)
- Radioimmunoassay (RIA)
- Fluorescence immunoassay (FIA)
- Luminescence immunoassay (LIA)
- Chemiluminescence immunoassay (CLIA)
- Immunochromatography (IC)
- Immunoprecipitation (IP)
- Western blotting
These assays all work on the same basic principle of using antibodies to specifically bind to antigens, but they differ in the way that they detect and measure the binding. For example, in an ELISA, the binding between the antigen and the antibody is detected using an enzyme that produces a detectable signal, such as a colour change. In a radioimmunoassay, the binding is detected using radioactively labelled antibodies, which produce a signal that can be measured using a scintillation counter. In a fluorescence immunoassay, the binding is detected using a fluorescently labelled antibody, which produces a signal that can be measured using a fluorescence microscope or plate reader.
Applications for immunoassays
Immunoassay tests can be widely used in a variety of applications, including medical diagnostics, environmental testing, and food safety.
They play an instrumental role in the diagnosis of diseases. Can be used to detect the presence of disease-specific antigens or antibodies in a patient’s blood or other bodily fluids, which can help healthcare providers diagnose and monitor a wide range of conditions, including infections, autoimmune disorders, and cancers. For example, the HIV test is an immunoassay that is used to detect the presence of HIV antibodies in a person’s blood, indicating that they have been infected with the virus.
They are frequently used for environmental testing. Helping to detect the presence of pollutants, toxins, and other contaminants in water, air, and soil samples. This is important for monitoring the safety of our environment and protecting public health. For example, these assays can be used to detect the presence of heavy metals, such as lead and mercury, in water samples to ensure that they meet safety standards.
They are vital in the food industry to detect the presence of foodborne pathogens, such as salmonella and E. coli, in food products. This is important for ensuring the safety of the food supply and preventing outbreaks of food poisoning. In addition, they can be used to detect the presence of allergens, such as peanuts and milk, in food products to help people with allergies avoid potentially dangerous situations.
Below is a list of some of the most common applications.
- Diagnosing and monitoring infectious diseases, such as HIV, hepatitis, and tuberculosis.
- Detecting and monitoring autoimmune disorders, such as lupus and rheumatoid arthritis.
- Screening and monitoring for drugs of abuse, such as alcohol, marijuana, and opioids.
- Detecting and monitoring pregnancy and fertility hormone levels.
- Monitoring levels of therapeutic drugs, such as insulin and blood thinners.
- Identifying and measuring allergens in food and environmental samples.
- Detecting and monitoring environmental contaminants, such as heavy metals and pesticides.
- Assessing immune system function and response to vaccines.
- Detecting and measuring hormones and other biomarkers for research and clinical studies.
- Providing rapid and accurate diagnostic results for point-of-care testing in hospitals, clinics, and other healthcare settings.
Overall, there are many different immunoassay procedures that are available. These assays play an important role in identifying various biological markers, this will help to better understand how different processes are controlled and regulated during normal and abnormal cell growth and differentiation.
The main principle behind all these assays involves the specific interaction between an antibody and antigen. However, method used for detecting these interactions differs from one method to the other. All these procedures are highly specific, sensitive and relatively easy to use.
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