Enzyme-linked immunosorbent assay (ELISA)

Definition

ELISA is a widely used laboratory technique that detects and quantifies proteins, antibodies, or hormones in a sample using enzyme-linked antibodies. It combines the specificity of antibodies with the sensitivity of enzyme-based detection to measure the presence of specific substances in biological samples, making it crucial for diagnosing diseases and monitoring health conditions.

5 Must Know Facts For Your Next Test

1. ELISA can be performed in various formats, including direct, indirect, sandwich, and competitive ELISA, each suited for different types of assays.
2. The assay utilizes an enzyme-conjugated antibody that produces a measurable signal, often a color change, when a substrate is added.
3. It is highly sensitive and can detect low concentrations of antigens or antibodies in complex mixtures such as blood serum.
4. Results from an ELISA are often quantified using a standard curve generated from known concentrations of the target analyte.
5. ELISAs are commonly used in clinical laboratories for diagnostics, such as detecting viral infections like HIV and measuring hormone levels.

Review Questions

• How does the principle of specificity and sensitivity apply to the ELISA technique?
  • The specificity of ELISA comes from the use of antibodies that bind only to their corresponding antigens, ensuring that the assay accurately detects the intended target. The sensitivity is derived from the enzyme-linked detection method, where even small amounts of the target can generate a detectable signal. This combination allows ELISA to be an effective tool for quantifying proteins or antibodies in complex biological samples.
• Compare and contrast the different types of ELISA formats and their applications in clinical diagnostics.
  • There are several formats of ELISA, including direct ELISA, which uses an antigen-coated plate and directly detects bound antibodies; indirect ELISA, which involves a secondary antibody for detection; sandwich ELISA, which captures the antigen between two antibodies; and competitive ELISA, where the binding of labeled antibodies is inhibited by the presence of an antigen. Each format has specific applications based on the type of analyte being measured and the desired sensitivity. For example, sandwich ELISA is often preferred for detecting large antigens due to its higher sensitivity.
• Evaluate how advancements in ELISA technology could impact disease diagnosis and monitoring in the future.
  • Advancements in ELISA technology, such as the development of multiplex assays that can simultaneously measure multiple analytes or improvements in signal detection methods like chemiluminescence, have the potential to greatly enhance disease diagnosis and monitoring. These innovations can lead to quicker results with increased accuracy, enabling healthcare providers to make timely decisions about patient care. Furthermore, integrating ELISA with point-of-care testing could expand access to diagnostic capabilities in resource-limited settings, improving overall public health outcomes.

Related terms

Antibody: A protein produced by the immune system that recognizes and binds to specific antigens, playing a key role in the body's immune response.

Antigen: A substance that induces an immune response, often a protein or polysaccharide found on the surface of pathogens, which antibodies specifically target.

Spectrophotometry: A method used to measure how much light a chemical substance absorbs by measuring the intensity of light as a beam passes through the sample solution.