Immunodiffusion is a laboratory technique used to detect and quantify

antigens In immunology, an antigen (Ag) is a molecule, moiety, foreign particulate matter, or an allergen, such as pollen, that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response. An ...

and

antibodies An antibody (Ab) or immunoglobulin (Ig) is a large, Y-shaped protein belonging to the immunoglobulin superfamily which is used by the immune system to identify and neutralize antigens such as bacteria and viruses, including those that caus ...

by observing their interactions within a gel medium. This technique involves the diffusion of antigens and antibodies through a gel, usually

agar Agar ( or ), or agar-agar, is a jelly-like substance consisting of polysaccharides obtained from the cell walls of some species of red algae, primarily from " ogonori" and " tengusa". As found in nature, agar is a mixture of two components, t ...

, resulting in the formation of a visible precipitate when they interact.

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.

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.

Other types

:# Single diffusion in one dimension (Oudin procedure) :# 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.

Notes

External links

* Biological techniques and tools Diagnostic virology Immunologic tests {{immunology-stub