Immunodiffusion Explained

Immunodiffusion is a laboratory technique used to detect and quantify antigens and antibodies by observing their interactions within a gel medium.^[1] This technique involves the diffusion of antigens and antibodies through a gel, usually agar, resulting in the formation of a visible precipitate when they interact.^[2]

Applications

Immunodiffusion techniques are widely used in immunology for various purposes, including:

• Determining antigen content
• Identifying immunoglobulin classes
• Evaluating antibodies
• Estimating serum transferrin and alpha-fetoprotein levels
• Comparing properties of different antigens

Types of Immunodiffusion

Single Immunodiffusion (Radial Immunodiffusion)

In this method, antibodies are uniformly distributed in an agar gel, and the antigen sample is placed in wells cut into the gel. As the antigen diffuses radially, it forms a precipitation ring with the antibody. The diameter of this ring corresponds to the concentration of the antigen in the solution.^[3]

Double Immunodiffusion (Ouchterlony Technique)

This method involves both antigen and antibody diffusing through the gel from separate wells, forming precipitation lines where they meet and react.^[4]

Other types:

1. Single diffusion in one dimension (Oudin procedure)

1. Double diffusion in one dimension (Oakley Fulthorpe procedure)

Advantages

• Cost-Effective: Immunodiffusion assays are relatively inexpensive compared to other immunoassays.
• Reliable and Reproducible: Provide consistent and reproducible results, making them suitable for routine diagnostic use.

Limitations

• Time-Consuming: The diffusion process can take several hours to days to complete.
• Sensitivity: While specific, the sensitivity of immunodiffusion may be lower compared to other methods like ELISA.^[5]

Notes and References

1. Web site: Immunodiffusion - Protocol & Troubleshooting - Creative Biolabs . 2024-07-25 . www.creativebiolabs.net.
2. Web site: Aryal . Sagar . 2022-07-04 . Radial Immunodiffusion- Principle, Procedure, Results, Uses . 2024-07-25 . microbenotes.com . en-US.
3. Web site: 2017 . Radial Immunodiffusion . dead . https://web.archive.org/web/20170807195715/http://www.edvotek.com/273_gallery.png . 2017-08-07 . 2017-08-07 . Edvotek, Inc. . photograph. Photograph of precipitin circles in a Petri dish during radial immunodiffusion.
4. Web site: Diffusion Patterns . live . https://web.archive.org/web/20191211044657/https://image.slidesharecdn.com/immunodiffusion-130121011208-phpapp01/95/immunodiffusion-principles-and-application-17-638.jpg . 2019-12-11 . 2017-05-19 . Immunodiffusion principles and application. Photographs of Ouchterlony immunodiffusion patterns showing stained precipitin lines of full identity, partial identity and non-identity.
5. Mujtaba . Mustafa G. . Baliban . Tara . Bhagu . Jamini . Herrera . Michael . A Laboratory Exercise Simulating Antibody and Antigen Reactions of the Ouchterlony Double Immunodiffusion Assay Using Inorganic Salts . Journal of Microbiology & Biology Education . 22 . 2 . e00103–21 . 10.1128/jmbe.00103-21 . 1935-7877 . 8442017 . 34594450.