Immunological Techniques- Types and Examples


Immunodiffusion tests are a type of immunological technique that use the diffusion of antigens and antibodies in a gel medium to form visible precipitation bands. These bands indicate the presence and identity of specific antigens or antibodies in a sample. Immunodiffusion tests are based on the principle that when an antigen and an antibody are mixed in optimal proportions, they form an insoluble complex that precipitates out of the solution.

Immunodiffusion tests have several advantages over other immunological methods, such as:

  • They are simple, inexpensive, and easy to perform.
  • They do not require sophisticated equipment or reagents.
  • They produce stable and permanent results that can be stored and examined later.
  • They can detect multiple antigens or antibodies in a single test.
  • They can differentiate between identical, partially identical, and non-identical antigens or antibodies based on the shape and pattern of the precipitation bands.

Immunodiffusion tests can be classified into different types based on the number of dimensions in which the diffusion occurs and the number of components involved in the reaction. The main types of immunodiffusion tests are:

  • Single diffusion in one dimension (Oudin procedure)
  • Double diffusion in one dimension (Oakley-Fulthrope procedure)
  • Single diffusion in two dimensions (Radial immunodiffusion)
  • Double diffusion in two dimensions (Ouchterlony procedure)

Each type of immunodiffusion test has its own applications and limitations. In the following sections, we will explain each type in detail and provide some examples of their use in clinical and research settings.