Ouchterlony double immunodiffusion

Ouchterlony double immunodiffusion (also known as passive double immunodiffusion) is an immunological technique used in the detection, identification and quantification of antibodies and antigens, such as immunoglobulins and extractable nuclear antigens.

The technique is named after Örjan Ouchterlony, the Swedish physician who developed the test in 1948 to evaluate the production of diphtheria toxins from isolated bacteria.

During this time the antigens in the sample extract and the antibodies each diffuse out of their respective wells.

[citation needed] The sensitivity of the assay can be increased by using a stain such as Coomassie brilliant blue, this is done by repeated staining and destaining of the assay until the precipitin lines are at maximum visibility.

As more antigen is added, the amount of protein precipitated increases until the antigen/antibody molecules are at an optimal ratio.