Enzyme-Linked Immunosorbent Assay (ELISA)

Enzyme-Linked Immunosorbent Assay (ELISA)

Definition

The Enzyme-Linked Immunosorbent Assay (ELISA) is a widely used laboratory technique designed to detect and quantify specific proteins, antibodies, or antigens in a sample, typically blood. It is a crucial tool in diagnostics and research for identifying infectious diseases, hormones, and other biomolecules.

Key Features

Mechanism:

• ELISA works on the principle of antigen-antibody interactions. The target antigen (or antibody) is immobilized on a solid surface (usually a microplate), and a sample containing the corresponding antibody (or antigen) is added. If the target is present, it binds to the immobilized component.

Types of ELISA:

• Direct ELISA: Involves the direct attachment of an enzyme-labeled antibody to the antigen coated on the plate.
• Indirect ELISA: Uses a primary antibody that binds to the antigen and a secondary enzyme-labeled antibody that binds to the primary antibody.
• Sandwich ELISA: Involves two antibodies; one captures the antigen and the other detects it, forming a “sandwich” complex.

Procedure:

• A sample is added to wells coated with specific antibodies or antigens.
• After incubation, unbound substances are washed away.
• An enzyme-linked secondary antibody is added, which binds to the target.
• A substrate for the enzyme is added, resulting in a color change that can be measured spectrophotometrically.

Applications:

• ELISA is commonly used to diagnose infections (e.g., HIV, Lyme disease), measure hormone levels (e.g., insulin), and detect allergens or toxins. It can also be used in research settings to quantify proteins in various biological samples.

Advantages:

• High sensitivity and specificity.
• Ability to process multiple samples simultaneously.
• Relatively simple and cost-effective compared to other assays.

Conclusion

ELISA is an essential tool in clinical diagnostics and research, enabling the detection and quantification of various biomolecules with high accuracy. Its versatility makes it applicable across many fields, including immunology, microbiology, and biochemistry.

References

1. MedlinePlus. (2022). Enzyme Linked Immunosorbent Assay Blood Test. Retrieved from MedlinePlus.
2. Healthline. (2023). Enzyme Linked Immunosorbent Assay: Purpose, Procedure, and Results. Retrieved from Healthline.
3. Thermo Fisher Scientific. (2023). Overview of Enzyme Linked Immunosorbent Assay. Retrieved from Thermo Fisher.
4. StatPearls. (2023). Enzyme Linked Immunosorbent Assay. Retrieved from NCBI Bookshelf.