What is the Difference Between Elisa and Elispot

The key difference between Elisa and Elispot is that Elisa is an enzyme-linked immunosorbent assay that determines the total concentration of secreted signalling proteins, while Elispot is an enzyme-linked immunosorbent assay that detects individual cytokine-secreting cells.

Elisa and Elispot are two enzyme-linked immunosorbent assays widely used in medicine, plant pathology, biotechnology and different pharmaceutical industries. In these techniques, a protein analyte is detected by an antibody directed against it. Elisa is the most popular enzyme-linked immunosorbent assay used in laboratories. On the other hand, Elispot is an enzyme-linked immunosorbent assay that is not used instead of Elisa but rather used in addition to Elisa in laboratories.

CONTENTS

1. Overview and Key Difference
2. What is Elisa
3. What is Elispot
4. Similarities – Elisa and Elispot
5. Elisa vs Elispot in Tabular Form
6. Summary – Elisa vs Elispot

What is Elisa Assay?

Elisa is an enzyme-linked immunosorbent assay that determines the total concentration of secreted signalling proteins. It is a widely used analytical biochemistry assay that was first described by Engvall and Perlmann in 1971. This technique uses a solid-phase type of enzyme immunoassay to detect the presence of a specific protein in a liquid sample using antibodies directed against this specific protein. This assay is a commonly used diagnostic tool in medicine, plant pathology and biotechnology.

Mechanism of ELISA Test

In most of the ELISA test, an unknown amount of antigen is immobilized onto a solid support (microlitre plate) at the beginning. Then the matching primary antibody is applied over the solid support surface. This antibody forms a complex with the antigen (antigen-antibody complex). The antigen bound primary antibody can be detected by a secondary antibody that is linked to an enzyme through bioconjugation. In the final step of the Elisa test, a substance containing the substrate of the enzyme is added. If there is a proper binding of a primary antibody to the antigen, a detectable colour change is produced by the substrate. Ultimately, this quantifies the antigen in the sample.

Furthermore, there are different approaches to Elisa, such as direct Elisa and indirect Elisa. Currently, various Elisa tests are used to detect human pathogens like Mycobacterium tuberculosis, rotavirus, hepatitis B virus, hepatitis C virus, enterotoxin producing E.coli, HIV, and SARS-CoV-2.

What is Elispot Assay?

Elispot is an enzyme-linked immunosorbent assay that detects individual cytokine-secreting cells. Cecil Czerkinsky first described ELISpot in 1983. It is a type of assay that focuses on quantitatively measuring the frequency of cytokine secretion for a single cell. It is also classified as a technique that uses antibodies to detect a biological or chemical protein analyte. Fluorospot assay is a variation of the Elispot assay, which uses fluorescence in order to analyze multiple analytes (more secretive proteins).

Mechanism of Elispot Test

In this mechanism, cytokine specific monoclonal antibodies are added to the wells of microlitre plates initially. Then the desired cells being observed are added to the wells. Later, the cells are incubated. During the cell incubation, the cells are allowed to react to any stimuli and secrete cytokine. The cytokines that have been secreted by the incubated cells will attach to the antibodies since the cells are surrounded by cytokine specific monoclonal antibodies.

To detect these cytokine specific monoclonal antibodies,  biotinylated specific detection antibodies are added to the well. Biotinylated specific detection antibodies capture the cytokine specific monoclonal antibodies in the wells. Moreover, streptavidin-enzyme conjugates are added to the wells in order to bind with the detection antibodies. In the final step, specific substrates are added to the wells. The reactions of enzyme conjugates and substrates produce distinct spots in the wells. These distinct spots are read on an automated ELISpot reader. Ultimately, this will further calculate the frequency of cytokine secretion.

What are the Similarities Between Elisa and Elispot?

• They are both enzyme-linked immunosorbent assays.
• Both assays detect specific protein analytes.
• These assays use specific antibodies to identify the protein analytes.
• Both assays use enzymes and substrates.
• They are used as a diagnostic tool in medical laboratories.

What is the Difference Between Elisa and Elispot?

Elisa is an enzyme-linked immunosorbent assay that determines the total concentration of secreted signalling proteins. On the other hand, Elispot is an enzyme-linked immunosorbent assay that measures individual cytokine secreting cells. So, this is the key difference between Elisa and Elispot. Moreover, in the Elisa test, the antigen is firstly immobilized onto the microlitre wells. In contrast, in the Elispot test, the antibody is firstly immobilized onto the microlitre wells. Thus, this is another difference between Elisa and Elispot.

The below infographic presents a detailed analysis of the difference between Elisa and Elispot in tabular form.

Summary – Elisa vs Elispot

Elisa and Elispot are two enzyme-linked immunosorbent assays widely used in medicine, plant pathology, biotechnology, and different pharmaceutical industries. Elisa detects the presence of a ligand (protein) in a liquid sample using antibodies directed against the ligand to be measured. Elispot assay is a widely used method for monitoring immune responses. It detects individual cytokine secreting cells using antibodies. It is both an immunoassay and bioassay technique. Thus, this is the summary of the difference between Elisa and Elispot.

Reference:

1. Horlock, Claire. “Enzyme-Linked Immunosorbent Assay (ELISA).” British Society for Immunology.
2. “ELISPOT.” ScienceDirect Topics.

Image Courtesy:

1. “ELISA types” By Allan.richard5093 – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “ELISPOT-en” By DadOfBeanAndBug – This file was derived from:  ELISPOT.png (CC BY-SA 3.0) via Commons Wikimedia