Indirect ELISA

Definition

Indirect ELISA is a laboratory technique used to detect antibodies in a sample by using an antigen-coated plate and an enzyme-linked secondary antibody. It is commonly employed in diagnostics to measure immune responses.

5 Must Know Facts For Your Next Test

1. Indirect ELISA involves two binding steps: the first to capture the primary antibody and the second to bind the enzyme-linked secondary antibody.
2. The signal intensity in indirect ELISA is proportional to the amount of primary antibody present in the sample.
3. The process includes several washing steps to remove unbound antibodies, which helps increase specificity.
4. Color change occurs due to an enzymatic reaction that indicates the presence of the target antibody.
5. Common enzymes used in indirect ELISA include horseradish peroxidase (HRP) and alkaline phosphatase.

Review Questions

• What are the main components required for performing an indirect ELISA?
• How does indirect ELISA differ from direct ELISA?
• What role does the secondary antibody play in an indirect ELISA?

Related terms

Direct ELISA: A type of ELISA where only one enzyme-conjugated antibody binds directly to the antigen.

Sandwich ELISA: An assay where two antibodies bind to different epitopes on the same antigen, 'sandwiching' it.

Enzyme-Linked Immunosorbent Assay (ELISA): A plate-based assay technique designed for detecting and quantifying soluble substances such as peptides, proteins, antibodies, and hormones.